Google love data. They like to know everything about you, your movements, your usage and inside leg measurements.
Another comparison you could make, to see the difference between MS and Google, is to look up how much resources chrome uses on a PC and then compare to Edge. Edge is vastly different.
Like you, I have seen a marked reduction in data since I arrived on WP / W10M some 18 months ago from android. Windows seems to manage resources much better than Android. Maybe, because the nexus is a vanilla rom, straight from Google, they use a similar system to windows insiders, to collect data about performance etc of the latest rom, which nexus do get first. Judging by the amount of security and bug fixes that come out all the time, the data for these fixes has to come from somewhere. And we all know the best place for testing is out in the wild!