>>provided it has the right programming on what to do in specific conditions

That's my exact point - you can't hard code in every single possible problem. And in case autopilot doesn't have sufficient data or programming to handle the situation it has no other choice but relinquish control to the driver, at a moments notice. Of course it could always try breaking with full force, but a) breaks might be damaged b) breaking is actually a bad idea, if any of the wheels are on a soft surface(like in my example, after a tyre blowout the truck has moved closed enough to the edge that wheels on one side are now on grass - applying maximum breaking force in this situation will actually tip over the truck, the correct solution is to keep going until the truck slows down by itself). The truck might not know what surface it's on or where it's going(say a bird hit the laser sensor on top), so the autopilot would fail spectacularly in this situation, which would not be very difficult for an experienced driver to handle.