The cut function is implemented in Lion and later as a result of modifying the paste command. If you copy a file as usual but instead hold down the ⌥ key in addition to the normal paste command - it retroactively cuts the original files as well as placing them in the new destination.
⌘+⌥+V = paste + cut in Lion.
This makes an accidental cut and no subsequent paste event less likely.
On Snow Leopard and earlier, the cut function is not part of Finder.
The thing that seems to be different is that CUT on OS X means it's gone now. Whereas cut on Windows means text goes away and files get copied for cutting on paste. The implementations seem quite similar for filesystem cut/paste operations in practice.
Assuming it's not a "patent thing", one could speculate that this is a "do no harm" design standpoint. Why cut something and then potentially lose or misplace it? Imagine the harm if you selected a few hundred files to copy them (or duplicate them) but inadvertently hit the X key. Instead of forcing you to realize a cat or toddler has cut a whole folder of files, the cut only happens when you paste with the option key held down to paste and then cut in one action.
