I think it is a lack of interest thing....I went to hospital today where my son was having a routine ECG.....ALL the staff in the department were predominantly women and ALL the complicated hi-tec electronic scanners etc were operated by women. These machines are as, if not more, technically involved and complicated than sound engineering eqipment.
There are no reasons why more women cannot get on the tech side of the music industry.
When it comes to theatre, the film industry, TV and radio women are pretty well represented behind the production scene using cameras, sound equipment, and in control rooms.

http://www.soundclick.com/bands/songInfo.cfm?bandID=687727&songID=5238055