Line/queue-cutters are the worst. And I already stand on the correct side of escalators, but it's definitely very un-American for people to walk up them, or for others to stand on the proper side.
That's actually one small nuance about Americans that shines a bigger problem. Whether all you Londoners are polite and nice or not when you speak or interact with others, I don't think you realize how many cultural norms are integrated into your society that are, inherently, polite and inclusive of others. In America, it's very much a "this is MY space, and I will not care for the regards of others because I earned this spot" or "I will get to where I need to get first, and I don't care who I cut off, run over, or speed past along the way" attitude prevalent and ingrained in our culture.
You all know not to do things like sit on the chairs by the door in a crowded train, or respect the queue, or stand on the correct side of the escalator to let people who want to get by get by. You all have a lot of society norms and standards that were established for the politeness and betterness of others in mind. There are probably countless more examples of it, but you're just used to it. I'm not, Americans aren't like that. Just think of all the times you have seen or heard how obnoxious, abrasive, selfish, and annoying Americans are, how they just make every place their own space and don't mind others. That's fairly rampant here, we all act that way with each other and most aren't bothered by it. I am.
So, I know people think I have this really obtuse idea of London and how people act there, but I think you all underestimate how much different and better, more polite, your society is for someone like myself. And, yes, there will be the miscreants, the drunks, the crazies, the loud-mouths, and the hooligans all around, but, all-in-all, you have learned how to give each other a degree of respect and space that I crave but do not experience here.