taxis in a big city isnt neccessarily level 4. True, theres no person in the drivers seat, but there are still things that restrict the operation of a Level 4 s

taxis in a big city isnt neccessarily level 4. True, theres no person in the drivers seat, but there are still things that restrict the operation of a Level 4 system, while 5 is supposed to go anywhere, anytime. Snow, Rain, Fog, even night could all impede Level 4 systems depending on the implementation's restrictions.