Also, parking garages have support columns all over the place and people manage to avoid them. The main issue with parking lot installation is the additional expense of having to elevate the panels high enough for vehicle clearance.
Even if Disney covered all parking lots and rooftops with panels, they wouldn't have enough to go totally solar. The lots aren't as big as they seem. Epcot is around 87 acres and TTC around 150 acres.
As somebody stated above, the #1 issue with solar as a viable significant energy source is that the panels are very inefficient in converting solar energy into electricity. The best commercially available panels seem to be about 22% efficient and most panels are around 15%. For solar to really be practical from the standpoint of panel area required, that number needs to at least double, if not triple.
Although it would be crazy expensive and ruin the night time view, probably what would make the most sense is to cover the moon with solar panels and relay the energy to earth via concentrated laser beams or something. Wind turbines are ugly enough but at least they don't take up that much of a footprint. There isn't enough viable land on earth for current technology solar to contribute a significant percentage of worldwide power demand. I guess barges out in the middle of the ocean could be an option?