actually it's even simpler: don't let humans drive. Even today's rudimentary driverless systems are already vastly superior to humans in terms of events per mile driven. (i.e. pedestrians killed)
Come to my city and see if Autopilot can handle it at rush hour with road side construction sites and double parked cars.
A law abiding driver that's paying attention to the road has miles more cognitive ability for safe driving than any autonomous system to date.