Second, taking power from self-propelled vehicles is a kind of hidden taxation or toll, except that it’s only indirectly money. Consider how much harder it is to walk on beach sand than sidewalk, or recall how hard it is to pedal your tricycle on the carpet, because a fraction of your transportation power is sucked away by the “road”. I haven’t done the math quantitatively, but multiplying the energy inefficiencies of the vehicles, the crystals, and the necessary energy conversion circuitry, I suspect everyone would be better off if the road charged an overt toll and purchased electricity from the grid.