Disney World doesn't want a guest to walk any more than 5 strides to get to a garbage can so they have them all over the place. Plus, plenty of people walking around with brooms and dust pans to sweep up messes. It really does make a difference.
The owner of the club I used to manage models a lot of things after Disney World and numerous trash cans was one of them. Sure, we had a few people puking in urinals, a couple spills, and the occasional trash left lying around but our club was the cleanest one in town and a major reason was because we had so many trash cans.