>The insurance state parks carry is for negligent upkeep - a bridge collapsing, a bear that was reported dangerous being allowed to continue hanging in campground ect

This isn’t a thing. General Liability coverage, which covers losses arising out of ordinary negligence, is. The state almost certainly self-insures a large amount of any GL claim.

>It is not because someone might try to sue for getting injured.

If someone is injured and alleges the state’s negligence contributed, GL is absolutely where coverage would like, but again, the state likely pays at least the first million of any claim.

Any municipality that opens a motor cross park will need to supervise it, or they will be sued the first time two kids who have no place on bikes wreck into each other for creating a place for an inherently risky activity where that injury could occur without providing supervision. The duty the owner owes varies based on the risk. It’s one thing to leave a skate park unsupervised, but you don’t see municipal pools unsupervised - this is why.

So now someone needs to buy and develop land, and pay to staff it. And the minute the staff doesn’t kick someone out for acting like a clown and that clown wrecks into someone, they’re going to get sued for negligent supervision.

Glad you literally have no idea how the stuff you’re talking about works.