Not sure it's standard but in my town it seems to be private roads (which also have no town road services). There was some issue a few years ago where to comply with E911 regs the town decided they needed to go around renaming common driveways for clarity. So instead of the houses on a shared driveway on Smith Road being 6A, 6B, 6C Smith Road, they renamed the driveway "Jones Way" and numbered them 1, 2, 3. The letter they sent was extremely clear that there is still no municipal plowing or other "road" services and it remains private.