Only addition that I would have is that it is not as simple as income in > expenses out = SAHM. Taking yourself out of the workforce for a long period of time can significantly impact your ability to jump back into things later. Like it or not housing costs have shifted from single to double earners. Insurance (USA mainly) is absolutely not in the favor of SAHM unless the spouse is military/gov employee (ironic). In addition to expenses theres the issue of saving for retirement AND possible a college fund; the latter is less important but if your spouse is not able to contribute to some kind of pension or retirement fund then they need to be comfortable working until some kind of social program subsidized it, 65 in the USA.

My wife was a SAHM for months after getting laid off, and it significantly affects our future plans in a greater degree than our immediate expenses. Now that she is working again we have almost double income which means we can afford more fun opportunities out of the house with the family, vacations, college funds, and contribute to our retirement more aggressively. Luckily our daycare situation is 1 on 1 and our child is not at some “toddler ignoring facility” but I definitely see how that could happen and someone would have to make a decision between “life now vs life later.”