Sure, but then you're talking about a serious edge case. Also have you heard the noise an AirTag makes? You can barely hear it in your house, let alone on a subway car or in public.
The scenarios in which AirTags would actually be useful are serious edge cases. False positives or inconveniences are very detrimental to use.
If my family visits and I give them my house keys while I go to work then I have to give up tracking them (when it would be most useful since I trust myself more not to lose them) or warn my guests the keys might start randomly beeping?