[tmh79]

"Uber is absolutely not on the scale of those companies, and most of the time they should probably be using off-the-shelf solutions when they become available."

I agree, but I'd also add that the state of the world in 2016 when most of these infra projects were launched is very different from the state of the world in 2020. Back then, uber was not easily able to run on a bunch of OSS/cloud native solutions, but now for sure its not just possible but likely the best/most responsible way to do it [source: worked there for 4+ years]