This could be due to a whole number of reasons, however, I really don't understand why Apple doesn't develop beacons that could be put in strategic places that would pick up air tags and send an update. Put a few wired units in the bowels of the airport where the luggage is handled (you aren't necessarily guaranteed a signal in this area) and voila, you're helping your users. Hotels and shopping malls would also be good candidates for this. I have a few tags that I ask my parents and other elderly relatives to carry on them. They know what the tags are for and trust that I won't use them to trace them unless necessary. Luckily this hasn't been required, but for a little investment, I know how to find my loved ones and if I have to track them, and if there were beacons of some sort that would help, that'd be even better.