If you're worried to the point of stupidity/paralysis ("be prepared to be sued out of existence") then you've already chosen to never drive even a manually-operated car, because you were overwhelmed by your fears. Most people don't have that attitude going on, so they already drive cars anyway, where they face constant daily risk of injuring or even killing pedestrians.
And some of them end up occasionally doing it, to many peoples' grief. For whatever reason, society didn't give up and decide the existence of cars was just too dangerous to allow. It's over a hundred years too late for to advocate against cars. By the time your grandparents were born, this argument (that we're having today) had already been settled.
How the vehicle got to be out of control is what everyone trying to establish liability will be asking. That it killed a pedestrian or driver is merely the motivation for asking.