Obligatory Sold a Story podcast link.
I can't help but feel that a lot of this is deliberate, the end result of decades of dismantling the public education system to further divide kids into the upper class in private schools, religious fundamentalists in home schooling, and everyone else abandoned to keep the population uneducated and in worse economic precarity.
Somebody please tell me that the kids are alright 
I would argue akin to Vietnam, the early leftist movements in the US didn't have the benefit of high literacy amongst the working class. As a result you have a lot of leftist folk music traditions where a song writer would take a popular song everyone probably knew, changed the lyrics, and then sang it and helped people learn it. The Preacher and the Slave, Dump the Bosses Off Your Back, or the pretty obvious 3fer of John Brown's Body, The Battle Hymn of the Republic, and Solidarity Forever.
Utah Phillips explains it pretty well in the opening of Dump the Bosses Off Your Back