The women's vs. men's disparity has been talked about for years in architectural circles and is a common problem for most any public facility, but is particularly acute in facilities where usage is high (airports), usage tends to peak a certain times (stadia) or places that used to have a higher proportion of men but now are more equal (stadia and airports).
Current building codes in the U.S. require a higher number of fixtures for women than men, but only do so for certain types of buildings (among them: stadia, night clubs, places of worship). Unfortunately, airports are not one of those types, this development is relatively recent and there is no requirement to retrofit (although a sizable renovation would require an upgrade).