I feel like there’s a second facet of this. Spoken English in old interviews and movies here in the States often featured an awkward, weird hybrid accent known as “mid-Atlantic“, and it really didn’t die completely out of movies until the 1990s. Until that time, it appears that Americans had some kind of inferiority complex about their regional accents.
Since then news readers in the USA have even adopted a much more genuinely American, specifically Southern California sound, that even began to seep into UK spoken English a bit. (Since about the early 2000s the BBC has started to let newsreaders with regional English accents into the club, which I really enjoy and encourage.)
It is not a native or regional accent; rather, according to voice and drama professor Dudley Knight, "its earliest advocates bragged that its chief quality was that no Americans actually spoke it unless educated to do so". The accent was embraced in private independent preparatory schools, especially by members of the American Northeastern upper class, as well as in schools for film and stage acting
I find the number of accents kind of exhausting tbh. But the real reason I turn off BBC is because of the fact that it's sports news half the time ... or a feel good story about a barber in Kibera ... or meta-news (we're in the news room and this is how we put together our stories). I wish there was just a radio station with news. BBC has the people to do it but they just don't do it. I'd much rather have inside politics about Zambian carbon credits but that's the type of thing that's like <1% of the programming.
Not to be confused with the actual mid-Atlantic (Philadelphia/Baltimore) accent which is basically the aggressive opposite of the transatlantic accent.
One that sticks out in my mind is the Coen brothers’ True Grit (with dialogue largely taken from the 1968 novel), which consciously avoids contractions—not entirely, but enough to result in a noticeable (though pleasing) aesthetic. Except that’s more of the opposite case—false archaism, rather than false modernity.
Saw the movie recently myself, and wondered if it's really representative of the vernacular of rough men on the frontier in the 19th century. By teachers in schoolhouses, sure, but by bounty hunters and criminals?
See e.g. the conservative pundit William F. Buckley Jr, who spoke with a really classic example of this accent (and was alive much more recently than most people who spoke like this):
He had an interesting history. I guess English wasn't his first language. And he spent some time going to school in England in his early teens. I'd guess he came by that fascinating accent honestly. Not quite British, not quite American. And he spoke with a melody, very flowing from one word into the next. It does make him sound a bit aristocratic.
Since then news readers in the USA have even adopted a much more genuinely American, specifically Southern California sound, that even began to seep into UK spoken English a bit. (Since about the early 2000s the BBC has started to let newsreaders with regional English accents into the club, which I really enjoy and encourage.)