One of the things that keeps me coming back to the Mudcat so often is the fact that it is a trans-national, transcultural thing. You keep on rubbing up against these aliens from the other side of the planet, and exploring the differences is part of the appeal.
That's one of the reasons why threads about that kind of thing pull in lots of posts. And sometimes feelings get ruffled, because as Frank poibnted out, these are prickly subjects.
And so far as America is concerned, one thing about living in a big pretty self-contained country is that it must feel like a world in itself at times. (I mean look at how there are "World Series" contests which are just the United States, with maybe Canada). Moreover of course the Mudcat has mostly Americans on board (look at the Mudcat locator for example).
Inevitably that gets echoed in the assumptions made by people posting. That sometimes feeds into a tendency toward American-teasing which probably isn't too helpful. When it's time to criticise a country (etc),it's best to go carefully if you don't belong to it.
Though of course the post that kicked off this whole thing, about America consuming more than its share of the world's food, was actually from an American, so that's no sure-fire recipe for avoiding conflict. (Incidentally, here's a link to the site with the statistics that I think might have set the whole thing off. And it's an American site, financed by the Rockefeller Foundation. Can't get much more American than that, unless maybe you're Woody Guthrie.)