There's an effort in the airline industry to create a system called CommonPass for commercial airline travel. At present, the idea is to have every passenger get tested at least once, and ideally a second time when they arrive at their destination.
Where airlines offer pre-flight testing, it appears to popular with the public, but it isn't required. IMO, the problem there too is that the current system in the US is a bit of an inconsistent patchwork. There's a lack of consistency and clear messaging. Even the airlines are asking for more consistency.
https://www.washingtonpost.com/loca...d1d81e-23ab-11eb-952e-0c475972cfc0_story.html
I imagine WDW could also potentially allow visitors to use the same CommonPass, if it is implemented. It would take a massive effort though. the closest I think we have are the Trusted Traveler Programs (TSA Precheck, Global Entry, Sentri) , and those have a massive backlog. Even before the pandemic, they had a massive backlog dating from the last fed gov't shutdown.