We have the capability right now to make cars that enforce speed limits on their drivers.

We do, in fact, make cars with audible / visible / tactile alerts when the driver exceeds the speed limit for the road they are on, but we seem to have no appetite for buying cars that take the final step to actually automatically brake, never mind requiring all cars to do this.

I take this as a very strong indication that overriding driver preferences as in 1-3 will not happen any time soon.