Depends on the parking lot. One for a grocery store or a mall or strip mall? Sure, plenty of space that would make sense and could easily be worked around. But for a fast food joint or convienence store, most would need to be uncovered and just spackled with a few token areas for panels, and for most hotels I've seen more than half would have to do the same as well. These are sometimes the only places these people have for miles. These aren't easy to turn vehicles either, they usually look for empty parking lots because of how wide their turns are, and I've seen gas trucks hit dumpsters and randos driving uhauls hit gas pumps. If every panel isn't by default hung high enough that a semi couldn't accidentally hit it, it will get hit at least once within a year, and if there's a support beam within the bounds if the parking lot that will get hit at least once every 2. We still have plenty of good places to put panels though where they aren't at risk, every rooftop, all over signage, mounted like a Canopy plenty high up over various public areas, I just think it's logistically impossible to cover every parking area in the US with them without having so many exceptions that it becomes untenable.

On a slightly separate note, parking lot sidewalks are one of the few places I can ever find to sit down and relax on a walk. Everywhere around me that isn't a public park has gotten rid of sitting areas and public benches because they draw in loiterers, drunks, and drug abusers, or at least that's the excuse used. It's fucking sad that part of me is upset at losing what's objectively and already sad thing to latch onto.