There’s an Adventure Pass that is REQUIRED to park at trail-heads to hike, in Cali. Another tax/penalty/revenue generator, compliments of Big Brother.
If you have hiked at any time, you would know that there is work required to maintain the trails from washouts, more safe trails for the average hiker (e.g., adding steps, etc.), cleanup after slobs that leave trash, clean dog crap, overhanging limbs, brush, signs, and so on. This includes parking, of course, and maintenance of the parking area. I have hiked in many areas with the parking was non-existent except on the road shoulder, which is an accident waiting to happen.
Don’t get me wrong, I hate paying for parking and all the other fees, but for parks, national forests, and the like, they may actually be reasonable and warranted. The other ticketing examples on this thread, don’t much care for.