Maps was caught wardriving [2] with Google Streetview, linking Wifi access point names to physical locations early on. After getting caught, they settled for $13 Million last year.
Now Google Maps and even location services on all Android devices uses wifi scanning and bluetooth scanning as part of location triangulation. This is a constantly updating map of every SSID in existance, including unique radio devices in a given location.
Eric Schmidt, former CEO of Google, now heads up the DoD's advisory board on new technology [3]
[1] https://medium.com/insurge-intelligence/how-the-cia-made-goo...
[2] https://www.cnn.com/2019/07/22/tech/google-street-view-priva...
[3] https://www.defensenews.com/industry/techwatch/2016/03/02/go... ||| https://innovation.defense.gov/Media/Biographies/Bio-Display...