Why would women get paid to raise their own kids? You suggest it's because when done well, it has incredible value to society. What is that value to society? It's having functional, productive members. Women already reap the benefits of that by sharing society with other peoples' well raised children.

What I mean to say is that it's a web of mutual benefit. The gap is actually in all the people who don't have children, who are essentially free riders in this scheme, but that is offset by the fact that they pay taxes for things like schools, which they don't themselves consume, and lack of tax breaks that parents receive.