> Also I don't always see blue in new USB 3 cables and sockets, sometimes it's just black.
True, but if the cable is blue, that always indicates USB 3, at least in my experience—I've never seen a blue USB 2 cable. I think this is sufficient given backwards compatibility—how often do you specifically need a USB 2 device?
I very much doubt many "normal" people know to check the contacts.
