'The simple fact that you can compare Ubuntu (cost: $0) with OSX ($120 + custom hardware) and Windows ($117) is utterly amazing.'
Why? They're all competing desktop Operating Systems.
Also for hardware to be supported by your distributor, per other Operating Systems, your vendor pays money to that distributor - eg, Dell and HP pay Canonical to support Ubuntu.
"Why? They're all competing desktop Operating Systems."
Exactly. The fact that Ubuntu Linux can compete with operating systems that you have to pay for is an amazing testament to the skill, determination, and efficiency of all the people behind Ubuntu, Debian, Linux, GNU, etc. Especially when you consider they're not strictly organized under a company with strong leadership, such as Apple under Jobs or Microsoft under Gates.
Edit: Nevermind. I'd thought you meant it was unreasonable you can compare them - ie, the "if it's crap, it's free" excuse. On a third reading I realized you meant something else.
Why? They're all competing desktop Operating Systems.
Also for hardware to be supported by your distributor, per other Operating Systems, your vendor pays money to that distributor - eg, Dell and HP pay Canonical to support Ubuntu.