You underestimate the loss. It isn't just that businesses lose customers when the parking is full. People don't want to drive there and then have to turn back,

You underestimate the loss. It isn't just that businesses lose customers when the parking is full. People don't want to drive there and then have to turn back, so many won't take the risk. The lots may only be 70% full, but the chance that they might be 100% full is enough to make people go elsewhere. Customers expect dependable service. It's the same with operating hours. If you make your hours completely random, with a decent chance of being closed when customers show up, nobody will bother to make the trip.