Good luck building them. Many of the code dumps are incomplete (like dyld and ld64). They reference private apple headers and won't build without them. Granted, they can probably be hacked to build in some cases and having the source just for reading is still nice.

Steve Jobs proudly described the Mac as closed as opposed to Windows "open and fragmented" approach.

OS X is specifically designed not to work non-Apple hardware, even hardware that is perfectly capable of running it.

Parts of it are open source, mostly because those parts were an extention of existing open source software.

"OSX" is not free in any sense of the word.

Microsoft are still a far cry from the likes of GNU/Linux in terms of openness, but almost nobody would describe the Mac platform as "more open" than Windows.