I like how he inadvertently admits that engineers are compensated less well in part because they mistake their jobs for something fun they'd do anyway.
Those students selling paintball packages in the mall are paid on commission, but they sure aren't being paid well.
(The article isn't "why sales people are paid a lot", it's about why their pay structure is based on a commission structure).
But I'll bet those salespeople take more than a passing interest in buying a car, tending an estate sale, dividing up household responsibilities, or negotiating a lease.
I just don't think that means I should be compensated less well, or told that it means I should appreciate being paid (for my job, obviously) while doing something I love, etc.