Corn is cheap because of subsidies and the influence of processing and genetic engineering companies, not because it's easier to grow or process. If you're interested, check out the book "The Omnivore's Dilemma" or the film "King Corn," both of which explain the system pretty well. It's one of the things I dislike most about the US, actually. I have actually noticed that even things like cola taste better in Europe, and the only difference is they use sugar (from sugar beets) instead of corn syrup, so I can vouch that sugar is better for taste, and anyway studies have shown that corn syrup is somehow more likely to cause diabetes than sugar, etc. etc. so I'll personally stick with real sugar.
Anyway, this thread has gone way off from my original question. As I said before, yes, there are other types of flour in America, but they're not the "standard" type. If a recipe calls for flour in the US, everyone assumes it's standard all-purpose wheat flour. Other types are the exception. In the Czech Republic, on the other hand, if a recipe says "flour," it always specifies which type, because three types are completely common.
I'll leave the meat/bread/veggie issue for now because I think nutrition is a thousand times more complicated than most people think (reductionist science is always trying to pinpoint one or two substances that are "healthy" or "unhealthy," but it just doesn't work that way), and anyway everyone's body is different. I know I feel healthy if I almost never eat meat and in its place eat a lot of potatoes, rice, beans, and fresh vegetables. Other people feel healthier if they eat more meat, and then there's the kid who survived on nothing but jam sandwiches for sixteen years. I do notice that in general, vegetarians are very thin people, and people who eat a lot of meat tend to be bigger. But obviously the other factors in their diets affect this as well. Anyway it doesn't matter, I'll eat what I like and you can all eat what you like.