I don't really know. What I do know is people seem to misunderstand engineering team size as a simple sum of people working on the Uber app. It is not only the android/ios developer or the full stack developer who is an engineer in Uber. An IT administrator who helps people, technical or non-technical, with their work laptops also qualifies as an engineering team staff to the outside world.

What makes it your or my place to decide that? They're a private company, and they have plenty of profit motive for efficiency. If they didn't think they were getting value from all of those engineers, then they would fire them and save themselves some money. Or are we going to argue that corporate executives aren't greedy enough?