While compensation and work product are great metrics for economists to argue about, they aren't the only factor driving people. In fact, I think in most instances work output has no correlation to compensation.
People instinctively do things for seemingly intangible reasons that apply in various circumstances. They figure that the best workers are more likely to get promoted, will get the best shifts, want to help their coworkers, are less likely to get laid off and have personal standards.
Think of it this way... soliders, even conscripted soldiers, commit acts of bravery that are above and beyond the call of duty in combat. Instead of staying out of the line of fire, they charge machine guns, throw back hand grenades, and rescue wounded comrades. To an economist, these things are completely irrational or crazy, because all of economics is focused on studying or manipulating a datapoint on a supply/demand curve.
Life is more that supply/demand. Economics influences life, but doesn't consume it.