I wouldn't call either of those "the most widely used UNIX distributions in the open source world today".

Looking at the Apple website we see, that that line is almost an exact quote. Let me tell you that that line is nothing more than Apple marketing lingo for 'many people own an Apple running OS X and OS X is based on a modified version of FreeBSD, therefore it must be the most widely used UNIX distribution.' Ah! But FreeBSD is not UNIX, "FreeBSD is a UN*X-like operating system" (source: http://www.freebsd.org/doc/en_US.ISO8859-1/books/faq/introduction.html).

Fedora Core 1? Pah... lease! Sure, quite a few people have made the switch but there are still too many people using Slackware, Debian, Gentoo, Mandrake, etc to even come close.

OS X and Fedora are both non-standard so why *should* the defaults work? I would expect that you would have to work to get things to install in a standard way.