My understanding is they’re a Bluetooth device that do not have direct Internet access on their own; how is their location being updated if you’re not pairing with them to allow them access to your device?
Apple allows them to connect to any device in the “Find My” network and phone home, regardless of who it belongs to. Presumably that includes you driving next to someone with an iPhone if the tag is in your car. It’s supposed to also alert you f it’s determined to be travelling with you and the owner is not nearby, but I think that requires you to also have an Apple device, or install and actively use Apple’s Tracker Detect app for Android.