They are a lot smarter. They got Windows for free, use like we do which we have to pay. And they don't care about trojans and viruses. I bet most if not all, use it casually for im, e-mails and skype.
They don't spend in front of the computer like for most of the day or for work.
Viruses ? So what ? Opps my pc is starting to slow down. Alright, let's reformat. No problemo.
Those who are aware of security, are even smarter. They use Windows free (100% clean) and make it legit.