Particularly someone asked whether Uber could scale the approach. I couldn't find how many cities in which Uber uses corrected GPS, except a 2018 Verge article that says "15, launching soon globally". Either way, seems like the answer is Google has the data to do it. And Google can bring it to every (non-China) Android phone.
But yeah, Google's post is very light on technical details. It'd be interesting to see if their approaches were similar.
Edit: also of note, Uber used server-side correction (at least in 2018), while Google downloads 3D tiles to the device.
What? Had a serious moment of deja vu because this has been done before: https://eng.uber.com/rethinking-gps/