Parking lots are dangerous to build over, for two reasons:

1) people cannot drive. The amount of dents or other damage from incompetent drivers done to a concrete-built park house is crazy, I don't want to imagine the damage they'll do to tiny aluminium/steel constructions holding the panels

2) people cannot drive. They underestimate their vehicle height all the time - just google for "can opener bridge". Just a couple days ago a truck driver massively damaged the lighting in a Munich tunnel because he forgot that the excavator on the flatbed was higher than the truck...