I think we agree on how geolocation by IP works and that it has faults, just not on whether to call that a "heuristic".

I'm not familiar with where those databases get their information, but unless they're somehow tracking users in real time, there's bound to be faults. When I VPN from New York to my closet in Chicago, there isn't any way for the database to know that. People travel and networks tunnel, and that's leaving aside users of things like Tor who've deliberately taken steps to hide who and where they are.

There are lots of ways to guess, some better than others, but not really any way to know.