He said "throw coal in a furnace", not mine coal. When I was a teenager I had a summer job keeping a coal furnace burning overnight. It's hard to underestimate the skill required for that. They probably could have trained pigeons to drop in coal chunks in return for bird seed. The best part of the job was the time it gave me to read programming books.
But he was talking to/about coal miners, not furnace stokers.
"They probably could have trained pigeons to drop in coal chunks in return for bird seed."
Yeah. Other than on very small scales, that job was automated out of existence a hundred years ago. I'm surprised to hear that anyone is still employed doing that, frankly.