This subject is actually very interesting to me.
Watching the AMA's tonight you just see so many Brits singing in what appear to be American accents.
One Direction, Sam Smith(who is incredible),etc..
I just always assumed it was either they were just copying the pop songs they heard from America or trying to appeal to the US audience.
But then I read up on it and it is the rhythm and the notes that force them to sing in a more neutral accent, which turns out to be "American"
But how do Americans, being a relatively young country, have the most neutral accent?
Really is a fascinating subject to read up on