They are also getting paid for every campsite reservation and many "free" permits that are first come first served. One example, the parking lot for Multnomah F

They are also getting paid for every campsite reservation and many "free" permits that are first come first served. One example, the parking lot for Multnomah Falls in the Columbia River Gorge requires a permit that allows you to enter a rest area off the interstate during a specific one hour period that also serves as the parking for the falls. You may then stay as long as you like. The permits are free but I you pay a $2 fee per car to recreation.gov for the privilege. Despite being a highway rest area it is illegal to stop there from Memorial Day to Labor Day without a pre-purchased permit. I generally avoid the area during high season so I have no idea how strictly this is enforced should you ever have an urgent need for a toilet.