Re: All else being equal...
Marilyn again, on being shocked to find a colleague is paid 20% more:
"I just couldn't believe it. I was angry," she told The Guardian. "I felt like I had been punched in the gut."
Angry eh? I interviewed and hired a database guy once and, reviewing the hiring letter, was shocked to find he was to be paid more than me. Rather than call the police, I bided my time and found another job paying about 20% more than him. I think this is a normal part of people's careers.