Uber reinvented a ton of technology because of the idea that off-the-shelf solutions wouldn’t work at “Uber scale”. However, there was very little accountability for whether the in-house solutions were necessary, and working on these tools would get you promoted. So for every “Uber scale” problem that a team actually solved, there were a couple other projects that were just half-baked alternatives to the off-the-shelf software that they should be using.
It turns out that “Uber scale” is not really that large, despite the name. But engineers kept repeating “Uber scale” and building infrastructure.
The same problem occurs at the larger tech companies like Google, Facebook, Microsoft, Amazon, and Apple, but in different ways and to different degrees. And to a large extent, engineers are copying what other companies do, and bringing ideas from one company to another when they hang out after work or switch jobs. For example, you can bet that these companies mostly have their own containerization and scheduling systems, many of which are undoubtedly not competitive with Docker or K8s in 2020, but K8s only goes back to 2014 and all these companies are older. I’m sure Borg and Tupperware are great if you work at Google or Facebook but I’m also sure that they’re missing a bunch of tooling that you’re used to. Same thing with build systems. Bazel, Buck, Pants, Please, and that Frankensteined system that Chrome uses are all copies of each other but Bazel is the only one with a decent size community and ecosystem, as far as I can tell.
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.