Why are they so loud?
You're comparing apples to oranges. Again London vs your massive suburban house in a well off area isn't a good comparison. Compare some quint little village in England with where you live and the friendliness etc is much more even. America is a big place, just because well off suburban areas in Florida are friendlier, doesn't mean some inner city areas of America will be friendly. So unless you have visited every state and the poor and well off areas of each state, then you have no idea either.
Why don't you ask them. "The American dream" is no longer a thing. All men are created equal....unless you're African American, Hispanic, etc, etc.So tell me, why are there so many that want the American dream? Some have moved out there and at some point down the line has become an American citizen. Even though it has taken a very long time.
Americans are in fact so friendly, they even given away their hard earned shotgun bullets to schools for free. Only downside, you have to dislodge them from the walls and bodies first.