"Debt to income ratios"
The people who grew up during the Great Depression were very frugal and never wanted to take on debt. They wanted to pay cash for everything.
And look at the size of houses built in the 1950s vs. today. The square footage has doubled. People made due with less than people expect to have today.
And of course back in the 1950s very few people had TVs or multiple cars. Today families have 2 or 3 or 4 cars (one for each parent and one for each kid over 16). Plus Playstations, Birkin bags, and all sorts of stuff that didn't exist in the 1950s.
Middle class people today are living better than a lot of rich people in the 1950s.
Having two incomes is a choice in order to support a fancier lifestyle than in the past.
Even poor people today have TVs, microwaves, video games, air conditioning...
In the 1950s you had to go to a movie theater to experience air conditioning. Today, every house and apartment has it.
The culture changed also. People put purchases on credit cards at a drop of a hat now, and have no problem going into debt or declaring bankruptcy when it gets away from them.
In the 1950s, only an upper middle class businessman might have a credit card.