GPS tracking of cars is legal in many place. Those devices don't report their existence to the owner. Perhaps we should start there?
Besides, this tech is opening a tracking pandora box with social and political consequences that we can't predict.
I'm for banning without a licence on this one.
At most widespread use of it could be delayed until something smaller and even harder to detect is invented.
Most people don't own a gun.
I never heard, unlike in the valley where colleagues told me exactly that, that you have to be careful to not road rage because you don't know if the other guy is not an idiot packing.