The USA is hardly the centre of educational excellent or high achievement. The fact that people like Donald Trump are popular in the US, or the right to bare arms shows that American educators hardly excel at the development of critical thinking skills in american citizens.
Why doesn't the UK recruit someone from Finland or Singapore? Or maybe a truely outstanding headteacher who works in the UK. At least the likes of Sir Michael Wilshaw has some idea of what its like to teach in an English classroom.