The same way you force them to buy a map.

Unless "I have to buy" is a mistranslation.

You don't have to buy a map, paths begins usually in villages or lead to them. Usually when I walk in an unknown place I can find some of the red signs that indicates a GR, sometimes with distances and names of places they lead to. I hiked a lot without a map, never struggled to find a GR, local people usually know about them very well.

Yea, I think this is what is interesting about this approach. It’s an optional tax If you don’t have the money you can muddle along or do your research but if you have money you can just support the trails by buying a map.

Seems easy and efficient. You don’t need to charge mandatory admission and collect money (like is done in the US) you just sell an optional map in local stores. Makes sense.

If you want to do a through hike in the US, don’t follow this approach. You can’t believe how much bigger the place is than the anywhere in Europe.

I have hiked the PCT without seeing another human for a week. Other western trails are more desolate.

Also backcountry trails are rarely marked, except at some trailheads. The government maps were mostly made in the 1970s and contain trails that done exist any more (and of course don’t include newer trails).

My preference is to carry topo maps + compass and carry a small GPS for emergencies if I cannot locate myself.

In Canada the typos are quite good but have in my experience even less trail or stream information.

In both countries I recommend planning trips with someone local who knows the territory.

Yes, and It has some interesting historical implications.

You can buy the hexatrek map for 50 euro, or each section for 10 euro each.

As a long distance hiker, I can promise that this monetary decision will result in wilderness rescues if not tragedies.

Even trails that have free apps there are people who try to go without...

It's inevitable that people will follow parts of the trail without the paper map. Perhaps hunting geo caches. Or perhaps looking for a waterfall they saw on Google maps or some website.

If it's in OpenStreetMap, they can easily follow established trails using an app they are used to. I.e. less erosion. And when they get lost or injured, use the app to self rescue.