This nuance is important; it emphasizes the real issue is not economics, but culture! We've created a society that values the pursuit of wealth and comfort more than family, and it's likely this system is not sustainable. Not everybody can be wealthy, because wealth is relative and mediated by what exists. If 30% of people want something and there's only enough for 3%, then it doesn't matter what the relative wealth is among these people: 90% of people won't be able to "afford" it, and that will never change. A post-scarcity society will never exist alongside consumerism; we'll simply take what we can have for granted and lust over the new scarcities.
Unfortunately many people who are not properly equipped to raise children (financially, temperamentally or otherwise) have lots of children and don't make it work. The result is a permanent underclass and a serious crime problem in many of our major cities.
One thing I think gets really overlooked is that college and job searches tear apart extended families, which in more traditional societies are a huge part of the child care strategy.
Monthly mortgage payments are the same though. (Lower interest rates, etc.)
Also building costs gone up. (The plague of single family homes, stricter building codes, higher quality requirements from buyers, while buildings are still produced using the old labor intensive methods.) And due to fucked up zoning building low-cost housing is just not happening :/
So folks are basically forced to buy expensive houses.
I'm not saying people shouldn't take the risk, but it does seem that more people are either not willing to, or the risk profile changed since 70s, or both.
The data for the past few decades (near universal fall in birthrates and increasing mother's age at birth) clearly indicates otherwise.
They didn't wait to have babies.
The world was simply much simpler.
The number of practically available paths forward were less. So why wait? Nowadays people are in an analysis paralysis, so they just wait. (Or try to find better mates, better jobs, better social groups/communities, move around more.)
And due to less homogeneity it's seems harder to find someone. (And probably is harder.)
Also the acceptable mortality was higher. Wars were more common, losing people due to illness was also more common, etc.
And nowadays we have endless alternatives to getting married. Single life is very enjoyable. (see Netflix et al :))
Not really sure what I'm going to be learning from them about raising children in the 21st century.
1. Inverse relationship between household income and fertility rate?
2. Enhanced child tax credit (US), child benefit (UK), Medicaid (kid gets sick?)
3. Insanely progressive taxes on income?
If anything the Korean system is even more intense; at least with American SATs or ACTs it's only three hours, you can retake them as many times as you want, multiple times a year, and getting into a mid-tier university for undergrad is still okay. South Korea has a university test that is eight hours long, only held once a year (so you wait a whole year to retake results) and the chaebols (the South Korean conglomerates that control the economy, like Samsung or LG) only really hire from top tier universities. South Korea has a university graduate unemployment rate of 25%, compared to the US at 4%.
Housing prices are 9x salary vs 4.5x salary in the 70s and it takes a while to save up. Personal data point: it took me winning an IPO lottery to start thinking about having kids for real. Having kids while earning minimal wage? Terrifying, especially in the US where getting yourself or your kid sick could bankrupt you in the blink of an eye - and if you want multiple kids you increase the risk.
So we think we have to have it all before we start trying having kids and have no sense of community whatsoever. Societal focus on hedonism and career leaves little to no time to raise kids. And at the end of the day you end up having no support from the society that slowly but surely ages.