I question the validity of the statement that this is “the law” in NY state. Just because a driver ed instructor made that statement does not make it a point of fact.
I saw such a sign at a park one day and asked about it to a friend. The answer he gave shocked me and I don’t know if it is true but he said that backing into a parking lot in some places is a signal between gay guys that the person is looking for a (how to politely say this) temporary park romance.
Don’t know if that is true but if you ever see a guy sitting in his car and it backed into a parking spot…