As far as I understand it, they aren't being allowed to drive. They are doing the equivalent of "ignore that, it's not a real obstacle" or "try to go around this way", and then the car takes that input into account and does the actual driving (steering, control of throttle/brake) on it's own as usual.
I don't need, legally, to demonstrate any knowledge of this to drive on US roads currently (or even, strictly speaking, to know what side of the road I should drive on).
No, I'm saying that no one should be "concerned that non-registered drivers in one country are being allowed to drive remotely in a different country" because they aren't driving.