Even if users of computers don't know any other shortcut commands, Ctrl-C is a very common one and the easiest for users to pick up. This is backed up with personal experience and little study of most people around my community.
I noticed pressing Ctrl-C once is no more common. Users tend to press it two or several times before trusting it has copied. I know you might be guilty of this as well.
Does it mean that users has lost the trust they have on computer keyboard shortcuts or that this is an implication that touch gesture will replace physical keyboards on a PC? Or do you think there is some other reason?