I am not sure what your point is. The statistical probability of a human crashing into a stationary object while parking is pretty high. If the statistical probability of the machine crashing into a stationary object while parking is lower, then it is sensible (and even advantageous) to allow the machine to do the job, even if it is not 100% perfect at it.

i would say that is not quite true. i know of a number of cases where people where getting out of their stopped automatic car (brakes applied) and forgot to put it into park before standing up.

Also people forgetting to use the handbrake in manual transmission cars and the car rolls away after some time etc or when they put it into neutral instead of park.

Not quite true? It isn't true and easily proven so with a few minutes research. One could say it's so close to zero that it barely factors though.