My problem with it is when private entities are allowed to boot your car.
One time in Berkeley I parked in a parking lot and walked across the street to pick up some food. I was gone 5 minutes and when I returned there was a boot on my car. There was an attendant in the parking lot who informed me it was private property and only for the businesses next to the parking lot. They wanted $150 to remove the boot. This wasn't city parking enforcement, it was a private party.
It's basically extortion. I get that they're trying to discourage non customers from using the lot, but it wasn't obvious it was restricted and clearly if they have someone in the lot full time, they could have warned me instead of immediately holding my car for ransom. Especially since I'm not from that area and I'm not familiar with local parking rules. It's purely an expensive trap.
I don't think this case should be legal.