I don't know the answer to this question, but it's clearly related to the fact that work done to maintain one's own household gets left out of pretty much every

I don't know the answer to this question, but it's clearly related to the fact that work done to maintain one's own household gets left out of pretty much every measure of costs or productivity. (I suppose it's probably some form of externality. I ought to study more economics.) Given traditional gender roles, this is one factor that has historically led to massive undercounting of women's total contribution to the economy, which could potentially lead to distortions in selecting good public policy. (It's certainly not just a women's issue, but that's one of its big impacts.)