Thunderbringer: Oh... car autopilots... Those things are SCREAMING "accidents will happen". Because it doesn't matter how many radars, lidars, sonars, cameras, or any other possible sensors will you have - thing is software won't be able to react to a lot of unpredictable stuff. Like - a crash is unavoidable but bumping in one car means a few pizzas worth of damage while bumping into other means serious accident which can possibly kill a passenger or someone else, maybe even creating a chain of crashes. A human driver with some experience can see that and make a decision in less than 1/10 of a second.
Or when a kid gets almost right in front of your wheels and the only way to avoid killing him will be to crash into other car with severe damage but in that case everyone will be alive. Even making a computer to tell a water puddle from some super slippery oil or something isn't that easy. How to program a computer to drive dangerously and speed up instead of braking when a human sees easily that it's the best option to avoid collision or car spinning out of control on some ice or whatever. No computer can get even close to human intuition based on years of experience when it comes to dealing with unpredictable chaotic stuff.
And even for sensors - cities got a LOT of interferences. Even GPS signal can bounce off tall buildings sometimes and create echo.
And then, if you'll miraculously manage to make some super complex AI that will properly react to all of that without getting your car price into jet airliner range - oops... a simple error in the code. Calculating trajectory to Mars for an automatic spacecraft is waay easier than making a car to drive around a busy city. The code for the whole mission is waaay simplier. And yet... how many if those things failed because of simple error in software or data, like just trajectory data miscalculation or race condition or something, failing completely or partially?
Cars cannot even autopilot in 2077. If there is a vehicle parked right in front of them, they stop and wait until that vehicle is moved off the road. What hope do we have in 2020?