Rounding on someone because they are American should come as no surprise to anyone living in the UK. You also get the challenge of you're not from round here are you when you live 10 minutes up the road. My late wife, who was English, had to give up work because of the attitude of her colleagues in Scotland - and that was in a government department.
Face it the world has a fair share of idiots and unfortunately we seem to let them run it.