For those with Androids, by default, WiFi access point known locations supersede GPS **Even when WiFi is turned off** (the asterisk-encapsulated part can be disabled, but it's pretty difficult, and it annoys you about it all the time when you do).
If the complaining taxi drivers are using auto manufacturer GPSes, then I guess that's not the problem. But if they are using Androids, it could be. And for Pokemon Go users, it certainly would be consistent.
I turn off this feature mostly because it's very annoying when I fly on an airline with WiFi (always). When I land, it shows me in Phoenix, Dallas, Atlanta, or wherever the hub of the airline is, even though I'm somewhere else.
Google collects WiFi location data via crowdsourcing (see https://www.cnet.com/news/goog...)
This is a common problem when someone moves houses, or moves an access point from one place to another. It takes a long time for Google to update its database.