Have you ever heard of an economic model where everyone makes about the same amount of money regardless of what actual value they contribute to society? Of coarse you have...just pick an American factory at random and that's pretty much what you'll find. The norm for US factories is to have minimal or marginal income diversity, especially among blue collar workers. Let's look at this model in a slightly different context. Take entrepreneurship for example. Entrepreneurship usually takes a substantial degree of risk but can be tremendously rewarding if it works.
One of the most dreaded processes in business is the annual performance review. Rather you sit in the giving or receiving seat of the review, its usually a pretty uncomfortable process regardless of how well or poorly the employee has performed. The problem lies in the fact that most organizations (and subsequently managers) have very poor methods for gauging an employee's performance.