Just did the extraction, a real hole in the wall operation, with a tiny office to work out of, and the only one there someone who said he was a friend of the owner, and knew nothing about the operation. The owner already left for vacation (open season parking for the weekend?). The guy had a photocopied form with a handwritten amount paid, with no details listed. He said to call back Monday to talk to the owner, but I don't expect anything will come out of that; from past conversations with him. He just said "go back and read the sign, it tells you everything you need to know." He said there was no one else to contact about it; he didn't know the owner, and had that confusing bit about how he was contracted out by the towing company, as if it was a separate entity from him.
It appears it's an autonomous operation, and he wasn't called by the landlord, and not the individual stores. I believe it's simply an operation where the landlord gets a cut from the proceeds, but doesn't need to take any active role in calling for a tow.