Re: “… Any idea why it''s set up that way … “
Actually we do. Two words: Privacy and Anonymity.
1) The tag itself has no position locating capability.
2) The tag must remain untraceable to you.
2) The system relies on millions of iPhone users to “find” the tag, but they CAN’T discover to whom the tag belongs either.
3) The Finder is technically reporting THEIR position to Apple, but their actual identity and location must remain anonomous to Apple and ONLY the position made available to the Tag Owner.
4) The tag owner’s location and itentity must remain hidden to Apple, and the Finder.
This is all accomplished w/ some clever public/private key cryptology which is why it can only be performed on the tag owner’s trusted devices.
For a far better description, see this article:
Using Find My to locate missing Apple devices – Apple Support (AU)