A highway in OpenStreetMap is any road, route, way, or thoroughfare on land which connects one location to another and has been paved or otherwise improved to allow travel by some conveyance, including motorised vehicles, cyclists, pedestrians, horse riders, and others (but not trains …).
Curiously, this does not allow for informal paths getting mapped as highway=*. Unless trampling is considered “improving” the ground. Can you agree?
Try walking (or biking) across a field of undisturbed vegetation, then try to do the same when the vegetation has been “trampled.” The second is much easier, and so is an “improvement.”
highway=stop, highway=traffic_signals, highway=street_lamp, highway=toll_gantry… None of these is a “road, route, way, or thoroughfare”. Sometimes OSM keys don’t make sense. Not a huge problem.
Repeated walking through vegetation can cause a permanent path to form. With enough traffic, this could be a better path than intentionally created paths. The resulting way could be tagged with highway=footway and other appropriate tags.
I fully understand that this is not the documentation of the highway key. Nevertheless, it might get read by consumers new to the set, therefore it should spell out the full breadth of what is mapped as highway=* by the community.
Feedback here could not have been any more univocal. I am fine with this. The OSM highway key covers all of what in our local (Austria) law is considered “way/Weg”, from “freeway/Autobahn” to “social path/Trampelpfad”.
The page is also quite interesting, as it clearly shows how car-centric openstreetmap tagging is at the top-level.
Sometimes OSM keys don’t make sense. Not a huge problem.