Courtesy was the biggest difference in the British culture to me. Whenever I was bumped into/shoved (which was frequently) I never heard sorry, not once. It must be how they are raised so they don't know any different. I also never heard "thank you" or "thanks" if I did something courteous to others. In America people are usually outwardly thankful, but it's just not how the Brits act. I've been told that Americans are overly apologetic, though. I had to alter my thinking so I wasn't hurt by it.