These terms apply to people who know what Symbian or OS is.
Here, in Iraq, they call OS the "system", and if you want to buy an LG phone, they will tell you it has a complex system, take Nokia, it's system is much easier, they even don't know what Symbian is or what OS is.
Same goes on with Desktop OS, they think that Windows is the "default" OS everywhere, very very little who aware of other OSs.