Because of this: Government kills pay-equity inquiries, which is discussed at The Hand Mirror: Pay equity for women is just too expensive and Kiwipolitico: Women are paying for bankers excesses and No Right Turn: Women come last under National.
Numerous studies indicate that jobs performed predominantly by persons of color and white women pay significantly less than those primarily occupied by white men, even when the jobs compare favorably in terms of the level of skill, responsibility, experiences, effort, and formal training they demand. Such a pervasive pattern of salary differentials that correlate closely with the race and gender of the traditional job holders reflects the existence of cultural ideologies and principles that devalue the skills and abilities of women and men of color. The adoption of comparable worth standards of pay by employers will serve to reduce the wage inequities that have evolved due to historical and ongoing race and gender prejudice. Instead of setting salaries internally in accordance with the social status of the worker, employers would devise procedures for setting salaries in accordance with some agreed-upon criteria of job worth. Without such procedures, women and men of color are likely to find that their efforts do not really "pay" which serves as a disincentive to compete for desirable positions.
Laurie Shrage, "Equal Opportunity", in A Companion to Feminist Philosophy, Alison M. Jaggar and Iris Marion Young (eds), 1999