no pedestrians - too much trash anyway
no trucks - truck drivers will not insert restrictions needed, they always on road!
no bikers - they drive as it is possible, you cant use their tracks for twice
YES for train mode - recording OFF, navigation OFF!
Of course there is good to have at least one "others" mode for people, who want use Waze without car! Speed data collecting off for them and no recording allowed and maybe navigation off too, to avoid walkers from german highways.