Well, implicitly, I meant to hint that after one or two incidents, the lobby might convince the legislature to swing way too far in the other direction. (A very common tactic. You can't just hand liability from one party to another, not in an area people know and care about.)
A situation with pedestrians only doesn't require those traffic controls.
A situation with motor vehicles only does require them, otherwise there will be an increase in the number of accidents and unacceptable congestion.
The mixture of the two requires them only because of the presence of motor vehicles.
It's very simple, really.