Here's the pay paradox that Why Men Earn More explains: Men earn more money, therefore men have more power; and men earn more money, therefore men have less power (earning more money as an obligation, not an option). The opposite is true for women: Women earn less money, therefore women have less power; and women earn less money, therefore women have more power (the option to raise children, or to not take a hazardous job).

p. 11. - Why Men Earn More (2005)