I always thought that was the big difference between the United States and the "United Euro States"--the EU. The USA was founded "fresh" as a place in which states had a measure of independence but ultimately formed a nation at a federal level. That meant that it was in the nation's self-interest to help out states that ran in to trouble--paying off debts, etc.--because helping a state out would help the nation succeed.
The EU was formed with the baggage of centuries of bloody warfare among nations of wildly different and opposing cultures. I don't think that kind of history--and more importantly, the fundamental differences in culture--can be shrugged off in the 50-odd years that the idea of the EU has been around. It would seem that in practice, EU member nations are still very much about finger-pointing, and that can never lead to a successful federal bloc.
When a state goes bankrupt in the US, the other states pitch in at a federal level to solve the issue without divisiveness. When an EU member goes bankrupt, the other members demand blood.