Why didn't they replace the battery when the app complained?
How long would a thief really keep the AirTag anyway?
If the thief did keep the AirTag and you tracked them down, then what? A confrontation has a fairly high chance to have a worse result than losing some equipment. You could try to get the police to do it, but that's going to take more time, during which the thief is even more likely to ditch the AirTag.
Anyway, you're really swimming upstream trying to think of aigtags as an antitheft device. They're really for something lost, not stolen. Generally, they are specifically designed to not work well in adversarial situations.
Worst case scenario I report it to police directly and it tells them exactly where it is.
If something is stolen, if I don't know where it is that makes the problem 10x worse. At the very least the airtag shows where that item is (unless it has been found and thrown away).
Yes, and then wait 6 months for the police to get around to picking it up ...