That is not my understanding. The description for the manual scan specifically mentions trackers “that are separated from their owners” A colleague and I only found this sentence after having tried it for quite some time with an Airtag on his keyring. He then turned on airplane mode on his iPhone and my Pixel immediately found the Airtag. (We couldn’t make it ring tho, which was offered to me)

So I still believe the case you are describing is Airtags not with their owners. Maybe kids with Airtags connected to their parents’ phones. And like I said, the new feature where multiple people can connect to one Airtag might alleviate (not entirely fix obviously) that issue.