The iPhone is the only mobile phone running iOS so the only way to do market share for mobile phone operating systems means just counting the iPhone. If you're doing laptop OS marketshare it makes sense to just count Apple's laptops even though the same OS runs on other devices.
Uhm. iPhone is the only phone running iOS, but there are other devices running it too, so if you count instalations of iOS you should consider iPod touch and iPad, if you count only iOS on iPhones then the remark is valid: it's comparing apples to oranges.
... Their are other devices running OS X too, but if we're talking OS market share for laptops those devices don't get counted. They are comparing Android phones vs. iOS phones. Perfectly legit. Apples to apples.
