Niantic has been doing this for a long time starting with Ingress. I've maybe done a handful of scans in PoGo but as others have mentioned the rewards were just not worth the trouble. The rewards for doing it in Ingress were much better (at least back in the day).

I'm more split on my feelings towards it these days given our current political/social climate but part of me still thinks the idea of mapping the real world in great detail is a worthy endeavor if it can be done "right". I'd probably be more inclined to support it if they would release the data or make it publicly accessible for others to use but it being tied to the whims of a corporation (even one that's been less shitty than most) makes it hard to get behind.