So my friend who was an Imagineer for Disney in Epcot (no, I can't say his name. Even though he left he's still under NDA) and he told me this about the old World Showcase buses.
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I am looking at the omni buses now. The buses were removed because people were getting run over. we put a band on one bus and a bar on another then destroyed the rest. the band was called Junkanoo. They were running late one day and wrongly drove under the water bridge behind UK and ripped the roof off. Junkanoo was fired and the bar did not meet health codes. Both were converted into character buses. But that is why one does not have a roof.
Junkanoo did not like to work. they would call down shows for rain when there was no rain.
The accident was the last straw for them"