These trackers work by connecting to nearby phones, with the phone supplying GPS information and uploading it via its cell connection. So a Tile tracker will only get its location updated if someone with the Tile app is nearby, and since Tile users are relatively rare the tracking is only reliable in very busy places.

Apple and now Google trackers on the other hand build this functionality into the OS (or Google's near-OS bundle for Android), so if basically any phone comes within range of the tracker it will provide a location update.