You're conflating "Open Source" with FOSS.

FOSS is the mantra of a particular community-oriented software-development zeitgeist, where things are developed by a community, without a project maintainership per se—i.e. where "the project" refers to whatever the most active fork of the project is, rather than to the project as maintained by some particular BDFL.

FOSS projects are usually maintained under the aegis of one or more software foundations, like GNU or the ASF.

"Open source", on the other hand, means exactly what it says. Microsoft does Open Source. Apple does Open Source. Oracle does Open Source. It means exactly as little as the image conjured in your head by that list.