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.
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.
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...
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.
Unless "I have to buy" is a mistranslation.