because no one is equal and there is no such thing as equal work.. just your presence alone is sometimes a plus or minus for the people you are around, depending on the kind of people they are and the small eco-system your collaborations create. all those small plus and minuses factor into your worth. a good looking secretary provides the extra monetary value of being easy on the eyes, that adds to her hourly pay, compared to butt-ugly one that may do the exact same typing. that is just to mention routine work where you can isolate the work-output variables. in any job that requires creativity, there is no such thing as equality. it's also a fact women aren't very good stress takers. think how many stock traders and financial investing professionals are women. no i'm not talking the about the retail brokers that answer the phones at a financial institution.