The only people I've ever heard speak English in the USA are English!
Not true I believe. Don't the Bostonians and others in that part of the States speak a more grammatically correct English. We tease them for "gotten" but that is a correct past tense of the verb "got". Their lack of pronunciation of the "H" in "herb" is also more grammatically correct (from the French herbe pronounced without an H).
UK English has moved on - sometimes in bad way - innit.
We can and should thank the cousins for keeping English as it should be spoken (sometimes!!!!)
BD