But, in the end, you're ignoring the fact that the overwhelming issue with women and the trades is not getting turned down at the application phase, it's that they don't even apply in the first place.  As you say above, change is hard, and if you can expect men to belly up and do the stay at home parenting thing and face social stigma for their choice, then women can belly up and risk social stigma in construction ... and mining ... and sewage work ...  

But, they plain and simply don't.  Alberta's had a women only construction company, subsidized by the provincial government, for nearly 35 years.  They've had so few women come through the turnstiles that in 35 years they've hired enough women to cover ONE shift at ONE of Suncor's sites.  If they won't even apply in a totally controlled setting, at a company that only hires women, from top to bottom, the issue isn't discriminatory hiring policy, is it?