I'm aware of how it works and what is required. It used to do a much better job with "last location" before updating. It was also more consistent across places in iOS in which you can see people's location.
Sorry - what I'm saying - and again, if I could post screenshots without jeopardizing my own privacy, is that there are actually four or five different use cases, and different "states" of location. Find My (people), Find My (devices), [ignoring Find My Items for now], then... Messages ( [i] info icon in a pop-up/overlay), and Messages ( [i] info in lager screen).
Here's an example of current state of, for example, my mother (same exact behavior, with my wife, in the middle of nowhere):
- Find My People - No location available.
- Find My Device [iPhone] - Correct location.
- Find My Device [Watch] - Correct location.
- Messages [Person/small window] - No location available.
- Messages [Person/full window] - No location available.
There is also a "last location" contradiction, which was the biggest issue two weeks ago. That is, last location for each device + full person is different. Some show a last location (YES it's turned on/report last location), some do not. All are cellular devices that I'm referring to here - iPhone and Watch.