Alternatively, it's just because Google and Facebook are more consumer focused and I've systematically found their contributions, where as Microsoft and AWS are more enterprise.
Great, simple OSS catalogs: https://opensource.facebook.com/projects https://opensource.google/projects/explore/featured
I mean, just look at the hideous UI at https://opensource.apple.com/ Do they not care? https://opensource.microsoft.com/?sort=Stars&keyword=&tag=
Anyway, does open source give away any information about these companies. I'm trying to understand how to pick companies for employment/ graduating in a few months.