Not that simple. Kid walks into street and after computing scenarios only two possible outcomes will save one life, others kill both. Scenario 1: Wreck driver possible killing driver and saving child. Scenario 2: Hit pedestrian possibly killing pedestrian but saving driver. There has to be a line of code that will eventually prioritize the people in the car or out of the car and how does one decide that for all collisions? Does driver always take precedence? or do pedestrians? What about numbers like a car full of 6 people vs 1 pedestrian. It has to be programmed to make a decision because if it is forced to stay on the road then what if more collisions could be avoided by letting it veer off the road or lane? It sounds easy to just make it stay on the road but we could sit and contemplate scenarios all day long for both sides of the arguement, which right now with a human driver it is easy to just rely on their judgement. It isn't controllable from an outsider, but when you make everyones car make the same decisions, then how do you decide? If cars get locked on virtual rails then it will make itself so undesirable it won't penetrate the market anyways so we could avoid it all together.