I worked with the USFS, local water district, and several non-profits on how to upgrade or even just maintain a popular river section south of Denver. A few decades ago, it was basically only accessed by fishermen, but now it is popular with hikers, dog-walkers, picnickers, etc. The parking lot holds maybe 20 cars and then people start parking every damn place along the narrow dirt USFS road. People and their dogs shit everywhere, erosion is out of control, etc, etc. I asked the USFS employees if they could institute a fee to help pay for expansion/maintenance of the parking lot, bathrooms, bridges, trails, etc and their response was "No, it's too much of an administrative hassle." It's not just coming up with an access/permit/fee system and enforcing it, but even getting approval from higher headquarters. Now, there are places like Sedona, AZ that have a system of pay-to-use parking lots, trailheads, etc on federal public land that I think works well (from my perspective the fees are reasonable and the facilities are well-maintained at appropriate levels, ie nothing extravagant). So, I like the Sedona model, but I kind of understand the hurdles to get there - ie the inertia of a federal land manager that is used to a mostly hands-off model.