Would AirTags be useful if you lose your item in a unpopulated area? If I get it right, then AirTags send a Bluetooth-signal to other iOS-devices within the reach of Bluetooth. The iOS-device then sends the received message to iCloud and iCloud then messages the owner.
Now, I ask myself: If I lose an item in an unpopulated area, like for example in a wood, would I benefit of having an AirTag attached to it? Even if it's very unlikely that someone with an iPhone passes by?
Yesterday I made an trial. I got the impression, that an iPhone memorizes the last location on which it had contact to a coupled AirTag. I'm I right there?
If that's the case then the AirTag would be still useful as marker, where I parked my car or where I lost my wallet.
Your iPhone scans for both AirTags it knows and ones it doesn't, and updating the location for both ‘types’ of AirTag. This means you are correct that your iPhone would show the last location it knows for your own AirTags even if that location is not updated again by anyone else.