Sorry - I didn't mean it as a "blame the USA" (or blame anyone actually) thread. Just curious - it has been fascinating to read the range of replies.
No need to apologize. Lots of Americans do get it wrong, including the media. They often get things wrong about UK royalty, my favorite being a commentator saying that when when William married Kate, it was the first time a monarch or heir to the throne married a commoner since Anne Boleyn. Well, not exactly. For one thing (or three things actually), all of Henry VIII's wives, except for one, after Anne Boleyn were commoners. And there have been several since, including Elizabeth Bowes-Lyon and Diana Spencer (they had the courtesy title "Lady", but they were still commoners).
I do sometimes email media outlets in the US when they get these things wrong. It's just a little service I provide. 
My point was basically that British people get it wrong on their own, not from Americans.