I think you might be misguided in thinking that people should work twice as hard or as long. Isn't the most important factor how much and what they're putting out?
How often do you hear of people getting a significant raise and then handing some back because they do not think work enough or hard enough to earn it?
Am I misguided to think that people who use this as an excuse would never work twice as hard / twice as long when given twice the pay?