> a developer with a good knowledge of some lesser known language/technology might ask for a higher pay because he knows his skills are in demand and the employ

> a developer with a good knowledge of some lesser known language/technology might ask for a higher pay because he knows his skills are in demand and the employer cannot easily find somebody else with those skills for a lot less money. Given the huge productivity gulf between low and high ends of programmer productivity - a gulf that vastly outstrips the gulf between low and high pay levels - it stands to reason that as you move up the pay scale, programmers will tend to become net more productive in relation to what you pay them. If you pay twice as much for a programmer who is ten times as productive, you end up ahead of the game.