Automobile liability insurance is not manadatory in every state. Only some.
In the state I worked, commercial insurance/liability insurance didn't even ask the campground owner about anything other than, did they have a pool, was it fenced, was there a lifeguard on duty, other body of water. They did not ask if campers were allowed to ride bicycles, nor did they ask what breed of dogs were allowed. Some states may be different, but some of the things "blamed " on insurance are not accurate, just the owners preference and choice.