Mooner, unsalted butter does not have more fat, just no salt. I use unsalted butter for baking, but for everything else, I go with salted butter.
Wabigoon, it's not the amount of cows in America, it's about how the butter is made. Here is an article that explains the differences. Bottom line is that French, or Euro butter in general, has higher butterfat, and is cultured. American butter is just not as tasty, as good for baking, or much of anything else.
http://www.thekitchn.com/whats-the-difference-between-european-and-american-butter-229135
