You seem to be stressing the use of left foot braking whilst manoeuvring only, where I can see your point if you have to use
the accelerator. However, all my automatics over thirty years have engaged drive at idle, which is why the brakes have to be on before you can select a driven gear. My experience is also different from yours. I have first hand knowledge of only two runaway car incidents. The first was an elderly lady who jumped up the kerb into my daughters shop front, coming to rest against her desk. The second was a middle-aged businessman who leapt over an embankment and shot across a dual carriageway just in front of me. Both drivers had selected D instead of R and had reverted to right foot braking, but hit the wrong pedal. Of course when the car accelerated they just pushed the pedal harder.