The US does not have a political union by the way, not any more political than the EU executive and legislative branches anyway. The Federal government in the US reaches very well defined limits when it comes to touching on State authority and domain.
There's a difference between separate states under a federal entity and separate COUNTRIES under a monetary entity. I don't know why you keep thinking states have 95% rights and the Fed calls 5% of the shots - you know better than that.