Slavery may have been abolished in its literal sense, but aren't there many ways that we keep ourselves enslaved? One of the sneaky ways that we do this to ourselves is with debt. Not a karmic debt, or something like that, but financially.
It wasn't much of a coincidence that "company stores" emerged not long after the American Civil War, where the goods were priced so high that the local coal miners took a tab to get their groceries which ended up becoming greater than their salary. Soon, their entire pay was going to the company store and they were stuck with a debt bondage.
"You load sixteen tons and what do you get?
Another day older and deeper in debt.
Saint Peter, don't you call me 'cause I can't go.
I owe my soul to the company store!"
And I couldn't very well use the Big Bill Broonzy version without also including Tennessee Ernie Ford's!