Systems theorists say that "structure predicts behaviour". It's a bit trite, but also deep. Here's an example.
The US political system pretty much guarantees bad budgeting. Members of Congress are elected fairly independently. There is no party discipline, so each member will operate independently to maximise pork. This encourages horse-trading within and across party lines; nobody can be forced to give up something for a general good.
There's more: there's no incentive to balance the budget. The Executive's separation means that Congress does not need to concern itself with proper administration; it only doles out the cash. It has every incentive to ... maximise pork.
The dynamic behaviour of American government arises from the static structure. The drafters of the constitution drew on their knowledge of history and current affairs to try and avoid certain pitfalls. The US Constitution was state-of-the-art when it was written. It's less so now.
Countries where the Executive is formed out of the Legislative -- the Westminster system -- tend to have much stronger party discipline, because that discipline is required to pass budgets, enact legislation and to form the Executive. This tends to almost eliminate horse-trading, except between parties and independents. It's not perfect -- whole parties can engage in pork too -- but when policy emerges that benefits the many at the cost of a few, countries with party discipline will find it easier to adopt than those without.
Australia, which has the amongst the toughest party discipline in the democratic world, is also a reform leader. And I think a lot of that is explained by our constitutional arrangements.