There are cameras on the autonomous cars, I'm sure they'd do the trick just fine.
> Second, I still have no idea how on Earth would AC riding on a highway know that it is a black cat, not a black bag laying on the street.
LIDAR. A black bag laying on the street is virtually invisible to it.
> The bottom line: sooner or later AC will make a mistake.
True, but they'll have to make a lot of mistakes to be worse than humans.
> Last, who is liable when the system makes a mistake?
That's a good question, and not one that can be answered categorically for all classes of motor vehicle accident. I'd imagine that the driver of an autonomous car would be liable for their actions in the same sense that a pilot is when they place their plane on autopilot (or a skipper when the use an autotiller to steer their ship). If it can be proven to be poor engineering on the manufacturer's part, then likely the manufacturer will be held responsible. Otherwise it will probably be the driver getting sent to jail. Or maybe a mixture of both if both parties can be proven to have acted negligently.
> ...but I can throw myself under riding AC.
Yet you're incapable of throwing yourself under a normal car? Doesn't this contradict your previous point about sabotage?
Though admittedly sabotage is a very common concern with automatic cars - what if somebody papers over a street sign or throws rocks at the car whilst it is on a sharp corner? In reality, malicious third parties are of concern, but not any more than if the vehicle was not autonomous. Human drivers can still be distracted by noisy passengers, intoxicated by alcohol and blinded by lasers; all you're doing by putting a robot in control is swapping the weaknesses of one system for the weaknesses of another. Ideally, there would be a mechanical backup system which could be controlled by the driver in the case of an emergency, which would effectively make autonomous cars more reliable than normal ones.