Why Aren't There More Powerful Women in Retail?

On Forbes’ The World's Most Powerful Women list, there are but a handful who hail from the retail industry, the largest segment of the U.S. economy. Why aren't there more powerful women in retail? The National Retail Federation congratulates seven women on the list, although two, Spanx founder Sara Blakely (No. 90), and Tory Burch (No. 69), are primarily apparel designers that happen to have a foothold in retail.