Agreed, between Google, Microsoft and Apple, Apple is the worst in not contributing jack back to the world. I can't stand how Microsoft was able to get to their status using evil means but at least the Microsoft of today does give back open and free (at least in beer) products. Google is the best of the three in this regard. Come to think of it, not sure where I'd place Amazon on that scale.

Why would Apple have developers working on their hardware running Linux? Apple doesn’t use Linux.

They aren’t the biggest oss dev, but they have a decent amount of contributions. [0][1]

It’s hard to compare how much Google vs Apple contributes to open source, but not sure why anyone would think Apple “contributes back almost nothing.”

[0] https://github.com/appleopen

[1] https://opensource.apple.com/projects/