When Air France Flight 447 went down in the Atlantic Ocean after leaving Rio, a simple case of icing of one of the sensors caused the autopilot to change modes and when the pilots found themselves in a stall, they were either incapable or incompetent (or both) to correct the stall, even though had they done nothing at all, other autopilot systems would have saved the aircraft and everyone on board².
This is something of a paradox of automation. Human error necessitates the need for automation and automation begets incompetence and that incompetence necessitates the need for more automation.
We already live in a world where perhaps the majority of drivers on the roads can not operate a manual gearbox. If autonomous vehicles become the norm in say ten years, then are we likely to find ourselves with a new norm where the majority of drivers can not operate manual controls like the brakes, accelerator and steering wheel? If incompetence can cause a passenger aircraft to ditch into the sea, killing hundreds of souls, then surely it's possible that on a rainy day on a motorway somewhere, a similar kind of incompetence could also kill many souls in an accident. Just exactly what are the passengers in an autonomous vehicle supposed to do if a pedestrian suddenly steps in front of the vehicle and they do not have manual controls in front of them. There aren't a lot of moving things to hit at 29,000 feet but down here on the ground, there are all sorts of animals, people, shopping trolleys in carparks and many multiples of other vehicles which are moving.
As I write this on the train to work in the morning, there are probably at least a thousand other people travelling with me and all of us are blissfully unaware of the work being done by the drivers and guards on the train. I have been on a completely autonomous train and I can tell you that the experience as a passenger is identical. The difference between an autonomous train and an autonomous car though, are many many levels of complexity required to make it work. Quite obviously a railway train runs on a set of tracks, which means that the route is also fixed. Systems have been put in place which can mechanically stop a train and once a train has stopped, can switch off power to other trains within that particular block. Autonomous cars though, would not travel on fixed routes and because they'd all operate under their own power, installing a system which could shut down many of them all at once would be far more difficult to invent and far more difficult to control if it were to fail. Combine that with increased levels of incompetence and helplessness of the flesh and blood meatbags being carried along by all of these autonomous vehicles and the potential for disaster, must also increase somewhere.
The question is whether or not these are acceptable trade offs for society. When I was a wee lad, textbooks warned of the possibility that we'd run out of oil by 2010. That has not happened but at some stage it's pretty likely. That being the case, legislators in the future might like to consider banning petrol powered motor cars and if we find ourselves driving electric vehicles, the systems needed to shut those down and switch them off in case of impending disaster is simpler and easier to make a reality than for petrol powered cars. Legislators just might find it easier to coerce the public into autonomous vehicles through taxation and registration costs and so it might not be society which ends up making that choice consciously.
In addition to this, insurance companies with their armies of accountants and actuaries might also coerce the public into autonomous vehicles if the costs of insurance end to being significantly lower. This would become an economic decision rather than an emotional one, in the same way that horses and carriages disappeared from the roads in the opening decades of the twentieth century.
This then is the beast that shouted "me!" at the heart of the argument. Accidents will inevitably happen because even the most excellently designed systems will fail due to reasons of wear through use. Even an autonomous system with no human input at all will require maintenance which might not be carried out as well as it should, or eventually stop working because of grit, gunk, dust and dirt, and so at some point things will fail and break. Even though autonomous vehicles will still cause accidents in the future, I can still imagine that they will be better at driving us around than we can currently do for ourselves, and even though we might resent that we as blood and flesh meatbag will collectively become incompetent and helpless when something does go wrong, the day will come when that will be an acceptable price to pay and so we'd better get used to it and just step out of the way.