Maybe it's just me. But, if you stay off trail and away from the developed areas then:
1) You are not utilizing any of the "amenities" that they're charging for.
2) You can then justify not paying.
3) You're unlikely to get caught in acting on your justification.
Or, maybe, I'm just a cheap bastard that doesn't like being told what to do and then charged for the privilege. And certainly these things should be fought before they happen. But, once they happen then we all get to choose how we handle it.
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i really don't think that applies to me.