When it came time to get an overview of the codebase being purchased. The Google Maps car navigation iOS team had over 200 engineers. The Waze iOS team had 2
I don't really believe that. I worked at Google and the frontend teams were usually just a couple of engineers per target client, I doubt any projects had 200 entire engineers just for a single target client. Not even big projects like gmail has nearly that many.
Edit: If I were to guess Google maps would have 200 engineers in total, or at least 200 figure would be the entire team of frontend engineers for every target client, and then many more working in other roles. 1 engineer per million users is a pretty good rule of thumb for Google products, and a large majority of those will work on backend systems.