Thank you Fulltimestudent for sharing some American history I was not aware of. I googled it and read some and will read more later.
The mines were owned by Rockefeller Jr. Controlled by him while living in New York City. That area of mines he owned in Colorado had the highest rate of accidents and death from poorly shorned up (is that the right word?) mining structures. The miners were paid for the tonnage they produced, not how they dug it out. (Tunnelling was on their time/dime.) Meaning during those early years Rockefellar did not pay the workers for 'making' the tunnels to get the coal, they were paid for delivering the coal.
At the end of the video he sang he 'hung'... I was so afraid he was going to say he hung himself, but he said, hung his head in shame.
LL