The USA has at least five organisations promoting women in aviation and they have been around for decades. With all of the effort they put in to get more women in the pointy end, no US airline has more than 7% female pilots.
There are no barriers to entry for women wanting to fly in the USA and the airlines here have recruited women for 40 years.
With all of this effort the amount of female pilots cant break 10% at a US major.
Maybe, just maybe ladies dont really want to do it as much as men?