I am coming around to the idea that WiFi location would, sensibly, require signals from several APs, not just one.
Reason being firstly, if somebody moves house, when they fire up the router at new address, anybody using it might get the old location. That’s not only broken, it might also raise privacy concerns, as it may allow new neigbours to find the incomer’s previous address, without their knowledge.
There would also be a dillema, where exactly two WiFi signals are detected, but owing to circumstances such as above, are listed on databases as being hundreds of miles apart. Which one do you believe? I would suspect that in those circumstances, “location not known” would probably have to be reported.
It would therefor make sense to me if the rules required that at least two signals, that are already known on the existing databases to be close to one another, must be visible. Just guessing, as I have failed to find any documented evidence as to how it really works.