Macs "just work" for things where Linux doesn't. Photoshop doesn't run natively on Linux, that's alone is enough for many to choose OS X over Linux.
For many people the price difference (if it's there) doesn't matter.
For many people the price difference (if it's there) doesn't matter.
Linux is not as user friendly and integrated with the hardware as Macs. There are certain apps that are only available for Mac. Those are some of the reasons.