The developers who implemented cgroups worked at Google and upstreamed them.

The kernel is developed by Linux foundation and a variety of companies that have a vested interest in Linux like Intel, AMD, SUSE, RedHat, Google, Canonical. It's not a team of volunteers like it's popularly portrayed.

The foundation itself is also primarily funded by such companies.

> It's not a team of volunteers like it's popularly portrayed.

This is not correct. There is such thing as a *paid volunteer*.

Additionally, a large percentage of contributors are unaffiliated, independent or part of small companies:

https://www.cnet.com/tech/services-and-software/paid-develop...