People aren't paid based on how much value they create. They're paid so they agree to work for you, and then so they don't quit working. There is a relationship here -- you're willing to pay more to keep people working on more valuable things -- but there are tons of other factors that affect a person's pay. Previous salaries, other offers, and negotiation skills often affect pay far more than actual created value.
Think about it: if pay were based on how much value a person creates, why do different people on the same team doing the same job sometimes have wildly different salaries? Why do people often get raises after threatening to quit? How can salary negotiation ever work?
Think about it: if pay were based on how much value a person creates, why do different people on the same team doing the same job sometimes have wildly different salaries? Why do people often get raises after threatening to quit? How can salary negotiation ever work?