Besides, please consider: If equally qualified women really were available for 70 cents on the dollar, why wouldn't every company fire all the men and hire women instead, increasing their profits by an astronomical amount? You know the answer I usually get? 'Because men stick together and prefer to work with other men'. Yeah, like that would overcome the natural greed of the corporation's executives and stockholders; they'd hire baboons if they were equally capable, if they could keep that 30% for themselves. The 70% concept is great for headlines. Nothing else.
I'll tell you why:

- Women get pregnant; stop working and the corporation will still have to pay. (Atleast in Europe, don't know about the US)
- Women get time off to be with the kids, which equals less labour hours.
- Women tend to visit more the doctor, which also equals less labour hours.
- Women are more likely to be victim of harassment (sexual), this counts for them too.