Theoretically it's meant for tracking a lost item, I personally find the cost of Entry to be too steep for it to be worth using as a lost item detector, anything that would be worthwhile having it on tends to be significantly cheaper than the tag itself which makes it not really worth it.

The only use case I can think of is putting it in a luggage suitcase when going on a train or plane, but even then the first thing anyone who steals a suitcase is going to do is throw the tag out and even if they don't you still have to somehow get to the suitcase and retrieve it, which means you'll need to get law enforcement involved so you remain safe while doing so.

I put one on my tv remote. Now when my kids lose the remote, I just ask Siri to ping it.

I personally use a Samsung Smarttag to track my cat in case she ever manage to get out.

These days, it's not really that good at tracking people. If the tag goes out of range for too long, it randomly starts beeping. Also, if the person that being tracked has a smartphone, iOS or Android, their phone will have a notification if it detect the same bluetooth signal travelling with them for a certain amount of time. The companies had to nerf these trackers because people were complaining about them.

Ironically, if you use a custom OS like a linux phone or Graphene OS, you probably won't get these notifications. (I hope Graphene OS developers know about this by now and tries to implement their own tracker detection in their version of Android.)

Tracking your property, in case it gets stolen/lost.

tracking a pet

anything you might want to track/find. keychain. luggage. a purse. a pet. where you parked. they have card sized ones to put in your wallet. maybe they should put them in remote controls.

Probably because the airtags don't use GPS them selves, they are detected by a nearby phone and their location is interpreted from the phone's location.

How about reading the text to the end:

Months after the release of the AirTag, Apple launched the Tracker Detect app for Android phones, where users had to initiate the scan. Google and Apple since have continued working together to make it easier for Android phones to detect unwanted AirTag trackers and for Apple phones to spot Android trackers. Recently, Google rolled out automatic smartphone alerts for unknown Bluetooth trackers, similar to what iPhone owners receive for AirTags.

You don't need any app. I recently moved over from iPhone to android, and I have an airtag in my shoulder bag. My razr 2024 has to remind me every day that there is an airtag traveling with me. There is no way for me to tell it to ignore this one since it's mine.