Yes, sounds counter-intuitive, but the OSes (the platforms) are used extensively on things that are quite a bit like phones but aren't exactly phones. They're used so much so, that they change the market share picture.

They run all the same software. For 99% of programs, if they work on the phones, they'll work on the non-phone items (however sometimes less well). This goes for android as well as iOS as well as blackberry