I'm looking up maps of public national forests, to find nice land suitable for me to head out in and do recreation activities. Something that has been irking me, is that often the best access points and most convenient to public land for me are privately owned. I found a whole section of national forest essentially surrounded by private land, and for me to access it easily I'd have to cross through private land. Like why is this shit allowed for people to buy access points to public land, and then use it for their own purposes in addition to using the public land for their own purposes. Many of these people will have an effective monopoly of the public land, because they own the easiest access points and it's not easily available for anyone else. So they "control", or at the very least have a near monopoly use of the public land for their own purposes, a much greater amount of land than they actually own.

Is it a case of, they owned the land before the national forest existed, or these land are being traded privately to gain effective monopoly usage of a great amount of public land?