[schaggs]

My inference:

It is the nature of man to take jobs about which they are not passionate and that have no real meaning to them. They hate them (to one degree or another), yet continue to perform these ultra mundane daily tasks without really understanding why*.

Who knows exactly what Gord had in mind, but that's how that line struck and strikes me.

*ETA:
I don't mean the they don't understand the work they're doing, but why they do it when they hate it.

Because a man's gotta eat. Interestingly, you might be freer to stop doing what you hate if you were a machine. That's what I love about the juxtaposition of Man and Machine.

Man : I'm a man and I'm a man. I do what I hate and don't understand
Machine: I write about words - I find treasure or worse. I watch the end of man and I dream like a bird.