Maybe is because of what Steve Jobs mentioned about talented programmers having more power than CEOs as they can easily switch jobs.
(as an aside, this contrasts diametrically with Amazon, where i worked for a year for healthcare, not needing to because of Apple years' savings, but after a genomics startup i had joined ran out of funding, and wanting a new challenge; there skilled engineering types were presumed to be fungible assets for (not kidding) at least 7 layers of do-nothing bureaucrats making huge salaries...they could survive because sales on the amazon store extract something like the 30% royalty to amazon)