Don't you need very specific hardware to get Mac OS to work too? I think it is useful when comparing OS environments to make sure you are comparing on the hardware that is optimal for each OS. And you can get Linux optimal hardware from a lot more sources than Mac OS optimal hardware.
The biggest issue is that on the Mac side, it is really easy to get the OS and the optimal hardware together, and know that it "just works". For Linux, we have several small vendors, and a couple larger ones, that have Linux-advertised hardware, but most of the Linux optimal hardware doesn't advertise itself as Linux (Android phones/tablets, Chrome OS, etc).
The biggest issue is that on the Mac side, it is really easy to get the OS and the optimal hardware together, and know that it "just works". For Linux, we have several small vendors, and a couple larger ones, that have Linux-advertised hardware, but most of the Linux optimal hardware doesn't advertise itself as Linux (Android phones/tablets, Chrome OS, etc).