That's a power balance issue far more than a fairness argument. If my boss is happy to pay this amount for my level of work output, why should it matter whethe

That's a power balance issue far more than a fairness argument. If my boss is happy to pay this amount for my level of work output, why should it matter whether I'm spending 40 hours or 4 doing it? In fact, to suggest otherwise is downright Marxist, asserting that the value of my labor is the time I spent doing it, rather than the value someone else is willing to pay. Do you subscribe to the labor theory of value for goods, or just people?