Well, there is a difference in attitude, and it's very perceptible to western Europeans or Canadians who visit the USA. On the one hand, Americans tend to be warm, hospitable, and generous people...and those qualities are delightful. No doubt about it. I remember visiting Atlanta awhile back, and I found the southern hospitality of the people there just wonderful.

On the other hand, I find these very punitive attitudes in many Americans toward anyone who is perceived as a threat. Those people might be criminals, they might be foreigners, "liberals", "communists", "socialists", "Muslim terrorist", "right-wing nutjobs", "limp-wristed tree huggers", "faggots", Democrats, Republicans, Blacks, Whites...whatever... ;-) That's when the nasty side comes out of the emotionally reactive individuals in America who have an ax to grind. Are they ignorant? Well, sometimes they are and sometimes they are not. Sometimes they're quite well-informed and STILL just that nasty.

It may, as you say, be driven partly by economic insecurity. In fact, I'm sure that's a big part of it. It is also, however, driven by a very long tradition of solving problems through violence rather than through law and non-violent negotiation.