Nuclear is probably a difficult comparison, but in both cases it would indeed be about liability. Would the owner have liability? That would increase insurance by a lot, probably significantly make autopilot much more expensive to have.

Is the manufacturer liable? Autopilot would be too much risk and the manufacturer would demand users can only activate it behind the wheel, needs both hands on the wheel while getting a coffee infusion. The tool would lose its advantages.

Power plants aren't insurable because it would financially destroy any company in case of a leak or operating costs would become so high, that nuclear cannot compete anymore.

We maybe will get it one day. Waymo probably did it correctly. Limited road network, careful approach, learn what the problems are and expand on that.