Back then children were viewed as a source of cheap labor that could contribute to the household. Developed countries have changed their expectations as you hav

Back then children were viewed as a source of cheap labor that could contribute to the household. Developed countries have changed their expectations as you have noted. You can't produce a farm hand that can contribute cheap labor directly to the household at an early age. Now we have to produce skilled workers that can contribute to the society. Skilled workers that may not even do their own laundry before 18. As a result, the household just sees children as a large expense, where the benefits go to the society. There's a significant incentive to defect from this arrangement. Not to say the experience of raising a child isn't intrinsically valuable. But, the value of that experience is only enough to incentivize some people to have 1-2 children, and as we are learning now, not enough of an incentive to keep birth rates above replacement in advanced economies. We probably don't need to make children a net economic positive again, as the intrinsic rewards of the experience are enough of an incentive, it could be net neutral or slightly net negative and still get us above replacement. But, advanced economies will need to change the math if they want to fix this.