[Mononokay]

In any case, Apple doesn't allow outside contributors, which means they're fine.

[Wowfunhappy]

But isn't Darwin based on an open source BSD kernel?

[UncleEntity]

BSD license doesn't require you to release your code changes.

[Wowfunhappy]

Huh. I'm somewhat surprised Apple releases the source code at all, in that case. It's not required, and they don't accept outside contributions, so what is the benefit?

[stuaxo]

A great benefit of upstreaming code is that it becomes someone else's problem to maintain it.