It's very difficult to have a single income family with kids.
It's very difficult to raise kids with both parents working.
Historically, people in the countries that now have low fertility rates were much poorer and yet we're having far more children.
In fact, the countries with the highest fertility rates globally are very poor.
The situations are simply too different for your argument to make sense.
But in America, most millennials and gen Z are so stressed they cannot imagine a life with a dependent child.
If someone wants chimes in with a "avocado toast" comment, save your energy. We know about it. That $5 is not enough to pay the rent, let alone raising a child.
I recently had a similar thought. When I was a kid I remember a lot of emphasis being put on reducing and avoiding teen pregnancies, especially ad campaigns. This internalized the message that pregnancy is something to avoid.
But when I got older there was no ad campaign to try to undo that notion (if that's even possible). I wonder if there are now a bunch of adults going around with that same feeling internally.
I also remember the same thing about "healthy food" - if you eat these healthy things like milk, bread etc then you'll be fine. Now that I'm older I know that that was just bs. But no ad campaign for that either.
I think the real solution is education about the upside of having kids and normalizing parenthood in one's 20's as a good life choice and as being successful.