Some parking lots only have 6" to 8" thick asphalt, and that can be damaged by the heavy trucks going in and out. So to keep costs down, only the truck lanes, truck delivery entrance, and truck unloading areas have the 10" to 12" thick asphalt required to not be damaged by repeated driving over them by 14,000 pound axles on the larger delivery trucks.
Most RV's have less than 8,000 pounds on the front axle, and it is OK on the asphalt to have 15,000 pounds on the 4 rear tires without damage.
If I where the manager, and had to pay the bills to repair the parking lots, I would also want the truckers parking elsewhere. I don't think many of them will be stocking up with groceries when the park. Even if their family does spend money there.
Fred.