I found some South Korean coverage of the matter. I'll add more about this later. The media's reported proposed placement of the park was roughly as I figured above.
South Korean news articles about Disney considering building in South Korea in the mid-00s, translated automatically, with some edits for clarity:
Weekly Chosun (weekly edition of South Korea's oldest, most prestigious newspaper), 4/20/11:
"Construction of Shanghai Disneyland begins"
... Previously, in 2006, the Seoul Metropolitan Government tried to attract Disneyland to the site of Seoul Grand Park in Gwacheon, Gyeonggi-do. [Former president] Lee Myung-bak, who was the mayor of Seoul at the time, officially announced his intention to attract Disneyland to Korea and unveiled a detailed implementation schedule. However, [that effort] was put on hold due to problems with the balance of payments. In the end, Disneyland, which was trying to go to Seoul at the time, entered Shanghai.
Ilyo, 8/21/20:
"Kakao takeover failed… The story of how 'Ryan' almost became Seoul Land's mascot"
... In fact, Seoul Land went through ups and downs whenever the mayor of Seoul changed. The history of Seoul Land began in 1984. At that time, the city of Seoul built Seoul Land in Seoul Grand Park as a BTO (profit-oriented private investment project). BTO is a method in which a private business operator directly constructs a facility, transfers ownership to the government, etc. Seoul Land Co., Ltd. (Handeok Development), in which Hanil Cement holds an 85.67% stake, signed a 30-year operating contract with the Seoul Metropolitan Government for 20 years free of charge and 10 years paid.
When the 20-year contract for free use of Seoul Land Co., Ltd. ended in 2004, then Seoul Mayor Lee Myung-bak rejected [a follow-up] 10-year contract for paid use while planning to attract Disneyland to the site of Seoul Land. After a court battle in 2009, Seoul Land Co., Ltd. finally won the case with the Supreme Court ruling that it was not legal [for Seoul] to refuse the 10-year paid use contract.
PFSS, 6/18/18:
Did Korea's Disneyland Really Succeed?
Disneyland almost established in Korea?
- [Disney] was considering entering in 2006.
- There is a story that there was an attempt to build it in Gimje, but it was canceled due to farmers' opposition, but that is unfounded.
- Gwacheon [was] the most promising place for Disneyland/
- [Gwacheon] is right next to Seoul and has an excellent transportation network, such as the subway. Since the planned Disneyland site is owned by the city of Seoul, there were no major obstacles to promotion.
- There were problems with Seoul Land and Seoul Grand Park on the planned site, and the contract with Seoul Land was also an obstacle.
- [There was also] the question of whether [a Disney park would be] profitable [given that] Everland and Lotte World [theme parks] were nearby.
- In response, Disney gave up on a Gwacheon Disneyland, and made a sharp turn toward Shanghai.
Getty Images Korea, Official Blog, 7/14/20:
Getty NOW: Disneyland, why doesn't it happen in Korea?
... In fact, Disneyland in Korea [was considered] as well. It is known that he tried to establish a Disneyland in Gwacheon in 2006, but was blocked by various realities and eventually turned to Shanghai. Gwacheon is a suburb of Seoul and has excellent transportation, so it was not a big problem for the promotion itself, but there are large theme parks nearby, such as Everland, Lotte World, and Seoul Land, so it was questionable in terms of competitiveness. It is said that there were many doubts about whether it would be successful. A theme park has huge construction costs and huge maintenance costs, so [ultimately] it [may not be] profitable. In addition, in Korea, [planned new] theme parks were often canceled because the land was expensive or because foreign investment failed, so Korea even got the nickname 'the graveyard of theme parks', and Disneyland must have had various concerns in this regard.
Hankook Ilbo (major newspaper), editorial, 6/20/16:
Disneyland and Deregulation
... Disneyland is known to spend as little of its own money as possible, even if it provides design, operating technology, and content when entering overseas markets. In fact, when the city of Seoul tried to attract Disneyland to Seoul Grand Park in Gwacheon, [reportedly] Disneyland requested land for free. The place where Seoul Grand Park is located is a green belt and is subject to the Metropolitan Area Readjustment Planning Act. Therefore, in order for [Disney] to [have done] what it [wanted], [the city would have had to] give the land for free and release [Disney] from various regulations such as the green belt. Even if [Disney's] overseas [parks] expansion strategy is usually like that, it is clear that it is a huge privilege.
... Korea has also pushed for attracting Disneyland, but it has been sluggish. Seeing the opening of Shanghai Disneyland this time, the claim that Korea failed to attract it due to strict regulations appeared again. Even though [there were] serious problems such as the controversy over preferential treatment and damage to the green belt, it seems that everyone thinks that things will go well without regulations, perhaps because the president calls for deregulation whenever he encounters a chance.
Sky eDaily, 4/27/17:
Controversy over utilization of Seoul Land 30-year contract expiration
... As Seoul Land shows that it is entering a new business rather than investing in amusement facilities, there is also a claim that a new theme park should be attracted to the existing Seoul Land site. It is the opinion that international theme parks such as Disneyland and Universal Studios should be attracted [to replace] Seoul Land, which lacks safety and business feasibility due to stingy investment.
Kwon Young-moo (42), who visited Seoul Land with an acquaintance, said, "Seoul Land lacks [substantive/meaningful] characters or the symbolism of a theme park."
The city of Seoul has already tried to attract Disneyland to the site since 2004, but it failed due to the contract with Seoul Land. Since then, Disneyland was attracted to Shanghai, not Seoul, and opened in June of last year. Currently, Shanghai Disneyland is the fastest-growing Disneyland in the world and continues to be a box office [sic] success, with more than 5 million visitors. The number of annual visitors is expected to reach 15 million, and the economic effect is expected to reach 3 trillion won a year.
Brunch.co.uk, 6/22/21:
Top 3 foreign theme parks that Korea missed out on
DIsneyland is the world's first theme park and a representative foreign theme park loved worldwide as a theme park that seems to contain the whole world of fairy tales. In not only neighboring Japan, but also China [Disneyland is] known as a theme park that can [be] a big hit if it is attracted, [earning substantial] tourism income through Disneyland. In fact, Disneyland has been steadily preparing to enter Korea since the mid-2000s. It is said that it has actually decided to enter the site of Seoul Land located in Gwacheon.
However, with the decision to extend the plan further, it proceeded without consultation with Seoul Land, leading to a lawsuit. As a result of the lawsuit, the court ruled in favor of Seoul Land, and the plan to start construction of a Disney [park] in 2010 fell through. At this time ... Shanghai attracted Disney, saying it would provide not only the site for the construction of Disneyland, but also the cost of the construction, and eventually, Disneyland, which was supposed to be hosted in Korea, was built in Shanghai, China.
Business Post, 1/24/21
Shinsegae CJ Lotte, building a theme park, challenges beyond Disneyland
... There is also a case where a Disneyland was almost built in the suburbs of Seoul. In 2003 ... when Disneyland [indicated an intent] to build a new Disneyland in Asia, the Ministry of Finance and Economy, along with the Korea Tourism Organization, formed a task force to attract Disneyland to Korea.
Disneyland selected the Seoul Land site in Gwacheon, Gyeonggi-do as a candidate site and even conducted due diligence [studies]. In 2006, then Seoul Mayor Lee Myung-bak said in an interview with MBC that "Seoul Disneyland will be able to start construction in 2007."
However, the Chinese government began to attract [Disney] very actively by leasing [to Disney a large parcel of land] for 99 years free of charge and even establishing a state-owned company for investment, and as [regulatory disputes arose among] South Korean local governments, the [central] government, and the National Assembly, in the end, Disneyland was built in Shanghai, not Gwacheon.
The Quoo (Reddit-like post), 4/6/19:
Why Seoul Disneyland was canceled
In 2004, at the time of Seoul Mayor Lee Myung-bak, Disney had an idea to build a Disneyland on the site of Seoul Land and Grand Park, and I know that [things went as far as the imminent signing of the contract].
Two of the most important things Disney asked for were:
1. Relocation of the National Museum of Modern and Contemporary Art
2. Relocation of the zoo.
Well, anyway, the previous problems seem to have been resolved.
(In 1985, Handeok Development signed a contract for free use [of the land] for 20 years in arrears of donation + 10 years for paid use after 20 years.)
There may be other reasons, but I think the reason for the dissolution was not lack of [attractive] regulation or support, but [rather] the moment Shanghai attracted Disneyland, [negotiations with Seoul] ended.
There are 25 million residents near Shanghai Disneyland, and 330 million people within a 3-hour drive.
The population of Korea is 51 million.
[South Korea's] Everland, the 14th [most-visited] theme park in the world, had 7.42 million visitors in 2015, and Lotte World, which ranked 16th, had 7.31 million visitors.
When Hong Kong Disneyland was also announced, I thought Hong Kong Ocean Park was [doomed], but ... Ocean Park [proved more] popular than Disneyland. Although Hong Kong Disneyland is small ... it's [still] Disney.
[Things ended] the moment Shanghai attracted Disneyland. I think it was a [competition that Seoul couldn't win] even if regulations were lifted and enormous support was provided [by Seoul].
