It's nice that someone pointed out that TOTAL government spending in the US, state and federal, is comparable to European numbers.
The problem is we have a welfare state on the one hand, and a federal government that was designed to have a limited role in domestic affairs on the other. The separation of powers was designed to be inefficient so that the feds wouldn't dominate the states like they do today. The states also retained their sovereignty, so the feds cannot directly dictate to the states (in theory) like European parliaments can. The result is a very inefficient welfare state, as they go. That's one reason libs dislike our Constitution.