Stopping a safe, automated vehicle would be trivial. Just dress up as a road worker, and hold up a stop sign. Do it above a manhole cover, and you have easy access to the bottom of the vehicle. A remote human supervisor might not even notice what was going on.
Admittedly it seems just as trivial to mitigate with some more sensors e.g. weight sensors to detect the load being modified while stopped, cameras to detect aberrant movement inside the cab, etc.
And what would currently happen? Killing the road worker? No, every truck would stop and you could operate in the driver's blind spot. Autonomous vehicles won't have blind spots so that the operator can identify the theft much faster.
