From the low power models I've seen (which are still very much illegal, same as the most powerful ones) only work between 5 to 10 feet at the very most.
It's like when the companies place trackers in cars, we have to assume they have the best intentions in mind (it is definitely for the customers security right?!)
But if we, the customers, block them from tracking us by jamming the GPS signal, they assume we have the worst intentions in mind (surely we are dirty criminals right?!)
This is why I said it "feels" wrong.
I totally understand this and I agree when it comes to jammers this powerful.
My comment was about the low power models which only works for few feet, just enough for to cover your own car. Those are still illegal.