Actually people have been pushing around the idea for EV charging stations. Otherwise, billing people is difficult.
One legal complication is that most states have laws preventing you from profiting from reselling the power in a submetering arrangement. For example, an apartment complex might pay $5000 for power one month. There are a number of different billing schemes that they can use to pass the cost on but at least Texas law prevents them from billing in a way where the sum is over $5000. So the meter scheme has some trouble paying for itself.
Well, RV parks aren't subject to submetering law. In fact they have some trouble collecting from people using the outlets. A parking meter-type arrangement might have to charge like 10x what the power cost to pay for itself though. Still, it's not a bad project at all.