But if schools five years ago could do it, then I don't see how it would be much of an expense to Disney (unless costs increase exponentially due to the size of the concerned area but still).
Also I think concerns about it being 'darker' under the canopy would either be overstated or concern trolling. It's less obtrusive than going from outside into a parking lot. If people can't be trusted to drive under a shaded canopy, then they wouldn't be trusted to drive under trees, at night, to park, or to exhibit any basic maneuvering skills.