The subject of American musical authenticity is a tricky one. A while back I read an article in the New York Times about how there is evidence to suggest that Robert Johnson, the King of Delta Blues Guitarists, enjoyed playing pop songs and show tunes in his live sets, but recorded his protean blues numbers “because there was a market for ‘race’ records” at the time. If Robert Johnson was motivated by commerce to sing the blues, then there is no authentic blues voice — it’s all show business. Which is also the subject of Llewyn.
Coen Bros: Inside Llewyn Davis part 2 by Todd Alcott (spoilers abound)
Presumbaly Alcott is referring to this Book Review Essay from 2004 that notes:
Johnson himself, when Wald analyzed his recordings, was at least as concerned to quote and rework the jukebox hits of his day as to up the ante on weirder characters like Skip James… blues emerges as a variant of show business: performers worked different circuits, from vaudeville to tent shows, stealing moves and sounds to make sure that audiences got what they wanted to hear.