Because the location provider from Play Services is an alternative to having the GPS turned on and gives an approximate location. There are some replacements like this by Mapzen https://github.com/lostzen/LOST
Depending on where you live (like the US) your telco is happily selling of data. So unless you have your phone in airplane mode your location is out there.
I installed maps.me to give it a try... Very surprised that one of the settings is "Use Google Play services to determine your current location"