The question becomes who is the driver? A passenger is normally not liable in the event that a driver causes an accident currently. If your car is driving itself, then you're inherently not the driver, you're a passenger. Especially if driverless cars are allowed to be ridden in without needing to pay attention or assume manual control, which I believe is the end goal for this technology.

So if you want to hold drivers strictly liable for accidents, but the only person in the car is the passenger, then question still remains unanswered: who is liable?