That was not the only craziness of the day. Deep behind a housing development, we found a parking lot near a restaurant with a sign that read: private property, park at your own risk. This seemed odd to me. What risk could there be except that the owners don't want you there, in which case why not just say "no trespassing" like everyone else does? Why "at your own risk?"
Further on, we saw the sign below. It seems strangely precise.