Apple and Google know the geolocation of every WiFi network in the US at this point. They could use signal strength as an additional measure if GPS is not accurate enough (though I'm pretty sure it is).

Sure, the coffee shop might be a problem (since I'm guessing that'd be more than 10 minutes.) You could always turn it off (and a smart system wouldn't turn it back on 10 minutes later unless you leave and come back.)