Android phones are constantly scanning cell and Wi-Fi networks to improve Google's geolocation, mapping, and traffic services. Google/Niantic could direct players (by setting the portal locations) to areas that need more network scanning, beyond the network scanning their Street View cars do.
At Mozilla, we are trying to do something similar with our "MozStumbler" app [1] for community "stumbling" of wireless networks. You can compare Mozilla's network coverage of the Embarcadero map in the Venture Beat article at [2]. We also have weekly leaderboards to show who has discovered the most new cell or Wi-Fi networks at [3].