While the Apple software and players DO have a large chunk of the market, there are still plenty that prefer Winamp, or things like that, and players like the Zune and Creative Zen's, etc.. (Probably from legacy libraries, etc.)
But it IS weird to be on the other end of a PC/Mac issue where it actually IS Apple that is the dominating force
How humbling it must be for the Dark Force Imperial Stormtroopers to have to worry about Mac compatibility for a change...