Problem is discrimination against foreign visitors, not the entry fee itself.
All breathe the same air and use the same trails.... Therefore the fee shoud be the same for all.
Some countries even devaluate their currencies to be more competitive against other and promote their countries as destination for foreign tourists....
Of course , there are everywhere guys who want to take advantage of benevolent foreign visitors. These people shouldn't work in positions where they can make decisions.
Supposed, an avarage income in CL is USD 800,. in CL, than an entry fee for foreigners of USD 25 to TdP NP is about 3% of a monthly Chilean income. Crazy! Some people seem to think elsewhere money is growing on trees....
Of course, Southern Peru is worse tham Northern Peru und Chile.
Some Bolivian sights charge foreigners maybe USD .50 more. Why? This amount makes nobody poor and nobody rich. Just to show the local population how rich the foreigners are? To encourage some crooks to grab their part of the assumed wealth of the foreigner, maybe the illegal way, too?