I don't find a good solution to have to pay a license to have the right walk the path I walk everyday to go from A to B, that my grandparents walked (just as their own grandparents did etc...), a path that has been traced by the sole circulation of humans in a forest, that local people "created" and that is now part of a GR.
Maybe that's only a psychological effect in my person, because something in me is okay with the fact of paying a global tax that would fund every activity related to the maintenance of the trails and the protection of wilderness.
There can be a free permit register along the trail need to sign. This is fairly common for hiking trails in some countries. It may also assist search and rescue efforts.
If the permit only covers a small area and it's not at the trail head, through hikers will rather buy a permit that covers the whole route.