content: Except that OSX is free. I think that started with Mavericks (might have been Mountain Lion). Now they do occasionally force you to update the OS when certain software packages update like Xcode, but since the OS comes with the computer, you've basically paid for it once and you're done. They don't need to sell the OS because the App Store is their cash cow, although I honestly don't know what anyone would want to buy from there, at least on the computer side. I think MS wants to push 10 so that they too can try to make some lovely money from their store but I think that train left the station a long time ago.