[solardev]

I'm not sure how it works in other countries -- and I hope I'm not explaining something you already know -- but the US has a LOT of different types of public land designations (https://sgp.fas.org/crs/misc/R45340.pdf PDF page 9) and agencies to manage them (https://sgp.fas.org/crs/misc/IF10585.pdf)

Some, like the most prominent parts of National Parks, are specifically managed to enable easy access (and also ADA accessibility, like wheelchair-friendly paths). There are also preservation-focused areas, especially but not only Wilderness (our highest form of protection, designated by Congress, prohibits motorized traffic and most buildings, often no use of machines like chainsaws or ATVs, though most will allow pack mules and such). Many multi-use areas (National Forests, BLM land, etc.) also have minimal facilities, often just a dirt lot and maybe a pit toilet if you're lucky. On the other hand, some smaller National Monuments might have no accessible areas EXCEPT for a visitor center and parking lot, usually to protect some extremely limited or fragile resource.

The USA is HUGE and many lands are public and/or protected for various reasons, to different goals. Not every trail is a National Park, and not every National Park is there for hiking or backpacking.

And it's also not merely a matter of land designation. Crowding can happen even in designated wilderness areas, often the result of a place going viral or being in close proximity to a major city or whatever.