Windows and OS X are substitutes, that’s what makes this a fair comparison. You would have a point if Windows wouldn’t even be an option for those who ultimatel

Windows and OS X are substitutes, that’s what makes this a fair comparison. You would have a point if Windows wouldn’t even be an option for those who ultimately buy Macs and if OS X wouldn’t even be an option for those who ultimately buy PCs. Also: What stops PC manufacturers from creating their own OS? (Obviously not from the ground up but they could create a Linux distro ála Ubuntu.)