As I understand it, working in the kitchen at a restaurant has the following characteristics:

1.  It's poorly paid
2.  It has crappy hours (late nights, weekends, etc.)
3.  It offers few/no benefits (dental care, etc.)
4.  It's highly stressful, with bosses, co-workers, and/or customers all giving you grief.

Given these characteristics, the main reason I can think of as to why female cooks are staying out of the kitchen is that they are (drum roll please...) SMART!