There may also be inequality of information and negotiation skills as well. In Bob's scenario, maybe Bob doesn't know his value and is happy to take the job at

There may also be inequality of information and negotiation skills as well. In Bob's scenario, maybe Bob doesn't know his value and is happy to take the job at $10 per hour. Bill, who works with Bob, negotiated $50 per hour. Bill has no idea how much Bob makes. Bob took $10 per hour because he compared that to a market rate for workers in that industry. Bill knows that their skills are relatively rare and that their work creates a lot of value.