Why don't more girls apply to pilot training schemes? Can't answer for others but my reasons are as follows:
1) When I was a footloose and fancy free high school leaver, having a good degree behind me seemed like the most important thing for future job prospects, so university trumped flying school. Too sensible!
2) When I left university, no way could I (or my parents) afford to put me through flying school, so a well-paid, stable career was the focus. Too sensible!
3) Having had a well-paid, stable career for a few years I can now afford to put myself through flying school. But now I am also a wife and a mother, so it's not just about me any more. I have a really supportive family but there is no way I would choose to leave them for months at a time to go flying in Florida or NZ, not to mention risk their financial security. And why would I give up a great job, great family and social life and great hobby flying to be at the mercy of the likes of Easyjet? Too sensible!
I've had people say that maybe I'm not passionate about flying and that if I really, REALLY wanted it then I'd have sacrificed all of the above to achieve the dream, but I disagree. I love flying so much that it doesn't matter what I end up flying, the buzz is just being up there. I don't need an airliner, if I get stuck doing 90kts in a tin can for the rest of my days then so be it.