The problem with covering a parking lot with solar panels is that it's usually a lot more expensive than covering rural land with solar panels. The panels have to be mounted higher off the ground so vehicles can get beneath them, they're usually expected to have a reasonably visually-appealing design, and all the wiring has to be kept safely out of the way and inaccessible to pedestrians. This drives up costs.
If land was truly scarce, parking lot solar would be a good option but I expect most installations will use the cheaper option of just building solar farms a long ways away from people.
Solar parking lots also might make sense in situations where all the power is being used on-site, and it's cheaper in the long run than buying power from the local utility.
