Because in this instance, the argument/discussion is about the phone specifically, not Google Maps. When my phone is on stand-by, like when I'm driving and not using the GPS, the phone will rely on less battery-taxing things like triangulation, Wi-Fi AP's that Google knows (MAC/SSID ?). Google Maps would however use GPS when it is on, not when the user hasn't specifically turned it on.
It's you who's confused (as you said previously, no offence). The post you replied to talked about "I just drove half way across the UK. Google knows that because I was using Google maps", and the mention of not using highest resolution is about Google (not Maps) using other means to determine location. Clear difference between Google Maps and Google.
Silly technicalities, don't know what the downvote was for, was only trying to help your initial confusion :)
