Doug, while I agree with you that mere denouncing people with who one disagrees is silly, there is something about the US society that makes many people - let's just call them more misinformed than others.
To see that, we need a proper behavioral model - which I divulged time and again on this list. People are not utility maximizers, but transaction cost minimizers. That is to say, if they were to choose, ceteris paribus, between a small payoff that requires a minimal effort and a large payoff that requires a lot of effort - most people would choose the former. For example, facing a choice between McJunk available on every corner, and a gourmet restaurant finding which requires an intensive search and a long walk - most people would opt for McJunk.
Ditto for political opinions. Most people grab fast food for thought spoon-fed to them by the media and other sources instead of engaging in involved research of every political issue. Thus far, the US is no different in this respect than any other country. What makes the US different is the ubiquity of the fast food for thought dispensers and the homogeneity and attraction of their pablum - which is much higher than in most other countries.
In other countries the saturation of every day discourse with broadcasted "sponsored" messages, both commercial and political, is not nearly as high as in the US. In most other countries you typically have not only more diverse sources of various credibility, but also fewer sources offering fast food for thought. That is to say, you may encounter a variety of views and opinions, some of them adamant other casual, but few of them are expertly engineered for maximum reception. That situation forces people to do a more active search for information which becomes the norm.
In the same vein, the absence of spoon-fed televised entertainment engineered for maximum attention grabbing forces people to rely more on their own social and entertaining skills and that again becomes the norm. That is why you have more spontaneous entertaining social interaction overseas than in the US.
In short, people who experience relative shortages and uncertainty and are forced to rely on their own skills and efforts to obtain social, material or intellectual resources, tend be leaner, more active, more agile, more inquisitive, and more resourceful. By contrast, people who are spoon-fed pre-processed pulp engineered for maximum absorption tend to grow stupid, fat, and lazy. If more Americans than other nationalities fall into the latter category, they should thanks their own industry bending backward to meet every consumer want.
Wojtek