But pay does not depend on how hard you actually work.

Sure it does. My employer notices when I work hard. Since they want to retain me as an employee, they compensate me accordingly. Similarly, I were to _not_ work hard my employer would certainly notice and want to reduce my compensation.

Working hard is not the same thing as working long hours or giving extra of myself. Working hard simply means working intelligently, thoughtfully, and to the best of my abilities.