Greentext

Federal or state government owns it depending on the park. And the fee is mainly just to pay for maintenance on the parking area. No one is chatging you to go to yellowstone or the grand canyon. They are charging you to park there or use some special service like guides, campgrounds, or picnic areas. Generally speaking though you can just walk onto any national park without paying anything. Yellowstone is a bit of a special case in certain areas because they really don't want people wandering around off trail because they're lible to fall through the ground into a hot spring that will melt their skin off before they get a chance to even scream and then the park rangers need to spend time dredging what little is left of them out of the hot spring. So those areas generally charge people to use the raised wooden trails because of maintenance costs. But at most parks no one is going around checking people for passes. They're only checking vehicles.

Also the costs are very low if you're paying at the park. You can also buy an anual pass to literally every US national park for $80. If you're a senior then you can get a lifetime pass for $80 and an anual pass for $20. There are also all sorts of ways to get those for even more discounted prices.