I fail to see what OS X has to do with UNIX, certification or not.
The apps are all programmed with APIs and a mindset that has nothing to do with UNIX. OS X is about the pretty face, not what's underneath. Sure, you've got bash on top and pipes and sockets if you want them, but that's completely insulated from the rest of the system, it doesn't seem to work together with Cocoa side of things, beyond nice drag and drop into Terminal.app. BeOS is more UNIX-like than OS X is...
The apps are all programmed with APIs and a mindset that has nothing to do with UNIX. OS X is about the pretty face, not what's underneath. Sure, you've got bash on top and pipes and sockets if you want them, but that's completely insulated from the rest of the system, it doesn't seem to work together with Cocoa side of things, beyond nice drag and drop into Terminal.app. BeOS is more UNIX-like than OS X is...