I doubt that the majority of mainstream Android phone owners know what kind of OS they have either. Maybe more than Symbian/Bada but still...
D: there's this thing on Android too F: what's Android?? D: your phone!
Still way more of Android users know that they have an Android phone than Symbian/Bada. Actually most likely no less than iPhone users knowing the word iOS (doesn't matter that much in iOS ecosystem though).