You forgot to mention child support which is for up to 18 years. Also, nothing stops the woman from having a career, especially if she cooperatively shares 50/50 custody, but often they prefer aiming for nearly 100% custody because it increases their child support payments, and then still have the option to cry victim that they’re a single mother despite getting thousands of dollars a month and they’re actively preventing the father from being involved with the kids. Happens a lot.

As for a stay at home mom who doesn’t get divorced, she doesn’t need to be entirely stay at home for all 18 years.. kids go to school at 5 and can go to after school programs if necessary while she works. A couple years before that if the kids are in pre school she could get a degree or masters degree or work part time. So the career gap could be minimized.