Sorry for the confusion, I’m aware they don’t have the sidewalk tag and are not eligble, but they do however actually have sidewalks. If the sidewalk tag were added to these streets (as one could correctly do), it could cause a situation were a street has nodes because it has sidewalks, but due to multiple lanes and the sidewalks sometimes diverting some distance from the the actual road, parts of the street might not be reachable by foot.
Again, it seems that this tag is not widely used in Oslo so at the moment it wouldn’t cause any issues there, but I can imagine this being a case in other cities that are actually tagged correctly with sidewalk tag.