I read a book once about singing in present-day culture. I forget the name of the book. The authors did research that involved hiring subjects to come in and sing pop songs they had learned from recordings.

Invariably the subjects imitated the pop singer's technique exactly. Every nuance was duplicated. If that's how people sing popular songs nowadays, I'm not surprised that people imitate the recorded accent as well.

Really, how much is there to an accent? A different kind of R, a few vowels modified...
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I was on a cruise last year and had to get medical care. The nurse didn't realize I was American till I told her at the end of the visit.
She was suggesting OTC medications I had never heard of, and she didn't understand why I seemed so confused.

When I explained that I was American and had never heard of any of the medications, she was surprised and embarrassed. I have never tried to sound British. I just talk my own Wisconsin-Missouri hybrid.

I tell the story to show that accents aren't as deep-dyed as we think.