people in the past managed to raise kids on far less income than the average income now
If I could compare and contrast our society today with the society I grew up with in the 80's and 90's
Real median household income has risen about 20% since the 80's
Unless you didn't go to college, in which case your income has been stagnant or went down in real dollars.
Meanwhile, the cost to raise a child has increased by over 60% in that time.
In other words, it is 3 times more expensive to raise a child now than it was in the 80's. And that isn't even considering college, which has gone up even more. And a much bigger fraction of those jobs in the 80's came with pensions, which are not counted in those income numbers. Today that "extra" 20% you make goes into your 401k if you want a chance at a decent retirement.
There are definitely changing societal norms that are influencing this trend. But waving away the very real and significant cost increases is omitting a huge piece of the picture.
New crypt. See /usr/news/crypt.