If improving safety is the goal then the driverless vehicle companies are going at it backwards. Instead of having the computer drive the car most of the time and telling the human to take over in challenging situations they should have the human drive all of the time with the computer constantly monitoring and occasionally overriding the human's control inputs when necessary. Some mainstream vehicles already do this to a limited extent by controlling throttle, brakes, and even steering to prevent crashes. Let's keep expanding on that foundation; it's far more achievable than a true autonomous vehicle and would save more lives in the medium term.

http://www.thedrive.com/tech/9548/the-biggest-opportunity-ev...

There is a successful precedent in aviation. The latest fly-by-wire flight control systems treat the pilot's inputs as merely suggestions and will modify them as necessary to prevent departure from controlled flight, midair collisions, flight into terrain, and overstressing the airframe.