in a documentary we watched, made by Disney, it seemed there's extensive infrastructure on a lower level in the Orlando DisneyWorld. Maybe that's part of the reason it's not obvious.
That's definitely the case in Magic Kingdom, but in other parks its not quite so much, I guess in (edit from Magic to Animal:) Animal Kingdom, you don't truly need to hide it, since it makes the park look more authentic. I assume for Hollywood they just make the buildings look like they're part of a set... Leaving Epcot which can just make the surrounding countries cover any infrastructure...
Epcot is probably my favorite of the parks to be honest, there's so much that goes into it overall.
You get to walk around the underground backstage yourself if you take Disney's "Keys to the Kingdom" tour. Basically, everything the public sees of Magic Kingdom is on floor 2.
