Correction to my last post, Spitfire Mk.5, not Mk.25.
"I have control" is of-course right about the relative ease with which you can build and fly things in the USA. The difference, IMHO, is that between a large sparsely populated continent, and a small crowded island. Given that the prime concern of regulators will always be the safety of innocent bystanders, the approach is inevitably different. Ideally of-course, you'd be flying a British certified aeroplane in the USA.
G