But it is exactly because they’re cheap, widely available and work well. Before AirTags, I’m not sure where you could acquire the technology you mention, but probably through some specialized channel requiring at least some tech knowledge. Also purchasing from that channel would presumably look at least a tiny bit suspect, because you were purchasing spying equipment, not something that is marketed as a way not to lose your luggage

And I get it, I have never tried AirTags but they do sound great for not losing your luggage. It’s just that the illicit way to use them is so evident that it’s like those “face massage” vibrators