I don't know why you're being downvoted, because this is the truth. AirTags are cheap, always-on tracking tags with no GPS receiver of their own. The only way they can report their location is via the goodwill of the other devices in their monolithic ecosystem, something that can only be built via large-scale cross-manufacturer cooperation, or by unilaterally doing it as a dominant manufacturer with enough beachhead devices around the world to make the system worthwhile.