At least with the two pedal system, there is one for go, and one for slow, irrespective that one or two events in quite a few billion end up on the wrong pedal.
My sister is paraplegic, and has a one handle solution. Rotate the handle down for acceleration, and push the assembly in for braking. (the axial down the steering wheel braking controls the normal brake pedal, and the rotating the assembly around the steering column axis the accelerator pedal). Talk about power assisted braking, as your weight, under braking adds to the braking effort.
Have seen plenty of occasions where the action of the brakes would be hindered by failure to (and inability to) remove acceleration under a snap braking event.