Exactly.  If it were true that you could hire and retain a woman for only 76% of the cost of her male counterpart, and that a company whose visible diversity vastly outperforms 'conventional' firms, then anyone looking to dominate an industry would build their business to that pattern.

Yet it doesn't happen.

Firms such as Hay Group, Korn-Ferry, Towers etc. specialize in human capital management and have all identified the 'pay gap' as being in the range of 0.6-1% for equivalent roles and experience.  Still something to look at, but not something as sensationalist and patently false as the 76% nonsense.