British Columbia

Depends entirely on the state/country, but some places have a law where a plot of land that is surrounded by other plots of land must always have some kind of accessible path to it, in the case that the surrounding plots develop around it and box it in, leaving no route for the landowner to actually reach it. Cyprus, for example is such a country where they do this. Germany, where this trek took place, probably has similar laws(?)

I actually don't know, but that is what was going through my mind when I thought "who would mark this as a public access path?"

I don't know about the "marked... for legal reasons" part, but there are officially surveyed road allowances all over the place that have no actual roads or have "roads" that are impassable except with the right vehicle in the right conditions.

I live in rural Saskatchewan and my work as a school bus driver and my interactions with the municipality mean that I can point out lots of bad mapping. The official bus route mapping that comes from head office always has to be amended because it seems that they do not have the data to distinguish between all-season maintained gravel, seasonally maintained dirt, unmaintained path, and road allowances that a farmer is permitted to seed or a rancher is permitted to fence off. Google and others just lump them all together when displaying or routing.