Yes, I said it was used to track cell phones in low density areas back when they were simply enough for this trick to work, what I assume is that if someone back then had a cell phone/radio phone/sat phone or anything similar with a susceptible transmitter in the middle of nowhere-stan you could probably identify them via other means, or at least be able to classify them sufficiently.

That makes sense. I think I veered off into confusion from the comment about the inductively-powered LEDs.