It could be a hypothesis. I work in IT and there is a lot of outsourcing.

My hypothesis is that customs and social constructs take a lot more than laws to change. I mean, even in countries where on the paper women can vote, work and so on, many times it is the grandmas who ask the girls (and not the boys) to help in the kitchen. And it is your grandma, so you help even if it is unfair that your brother is sitting. And then life "happens". That is, either old relatives need caring or young children need caring, men usually don't want to hinder their careers by taking time of to do it, so since there is a need, women reduce their working time or chose careers that allows them to take care of those relatives. That is custom, not forced by law, but in a way, if you know that if you don't do it, no one would, usually you "take the hit".

In countries where you need a wage to eat, you prioritize eating. Once eating is covered, the need to be there is next. Amartya Sen (economy nobel) did research about microcredits in India and the diferences between lending money to men and women for the families. It is posible that the same hypothesis could be tested here. Customs make it that when family has a need, it is usually a woman who adapts to cover it. Like religion, those things take longer to change (and religions enforce old gender norms. Look at the pope and catholic church).

80% of swedish are lutheran. And look what lutherans said about women:

"Women are not to have authority over a man, but should receive instruction with submissiveness. The word “usurping” authority (taking hold of a position not appointed to) is the key here."

So maybe research on correlation between religion and customs might help explain (be one variable among several others).

Remember, in many places a mother that works outside home is considered a "bad mother" and that is serious guilt tripping and emotional manipulation.