Google location is still very good in buildings and subways because they wardrive open wifi routers to help triangulate you. So when I'm near a wifi router with a particular MAC address that google has seen before, they've got me.

Agree with you on high rises and false positives, but then again, if air is circulated in the building or everyone uses the same elevators, might be worth notifying them.

https://support.google.com/maps/answer/1725632?hl=en