An airliner is a vehicle with federally-mandated maintenance and inspection periods, operating in a tightly controlled space in which new vehicles entering and exiting are known and managed by controllers and in which the transport medium (air) by and large doesn't change characteristics much for the duration of the flight.
Versus an automobile with a robot driver that has to handle crazy pedestrians, dogs, motorcycles, cyclists and other cars randomly entering its area of travel, wide variations in road widths, speed limits, road surface texture (dry, sandy, wet, ice covered can all be encountered in less than 1/4 mile of travel), random road construction and other non-robotic drivers.
This doesn't mean that a solution is impossible, but to point to airliners to say "see, it can happen" is a bit of a stretch.
Schmidt and Matt address this in their arguments. For example, Matt mentions that the beverage industry will skyrocket because people can now "drive" home drunk. The human can't take over in an emergency in that situation. Pretty much every advantage of driverless cars that Matt listed are not possible if the human is required to be alert enough to take over. Further, the person I was responding to claimed he would never have to learn how to drive. If a human is going to take over in an emergency, s/he will still have to learn. Point being, the discussion at hand is about driverless vehicles without using a human as a backup.