The connection between the left and folk music, in the USA, stems from the series of concerts sponsered by unions in New York city, in the 1940s. The performers included youngsters like Pete Seeger, Cisco Houston, Leadbelly, Woody Guthry, Lee Hayes and Josh White. Those guys worked cheap and they were, all, well to the left of center.
Union locals, in other towns followed suit so Win Strake, in Chicago, George Britton, in Philadelphia and Sam Hinton, on the coast stared singing folksongs for their living. Oh, I forgot Carl Sandburg, who endd his poetry reading with a short folk concert.
But the people, whose songs these were, were as traditional intheir values as they had always been.
It was the left who politicized folk singing.