I think Niantic used Google Maps Data initially, as they were a Google daughter. Pokemon Go and its “predecessor” Ingress is all about data collection. Thats why there is a scan-feature where the user walks around and takes a video of the Pokestop. Thats was the whole point of these games initially, giving people an incentive to do free work for niantic to sell to other plattforms. Just like ReCaptcha is used for image recognition training.