It's simple: they didn't work as much. Typically one parent would go out and work while the other took care of the home. When the first parent got back the house would be clean and dinner would be ready. Work was over.
The work parent tended to socialise in the evening and the home parent during the day.
The home parent was essentially self-employed, working directly for themselves and the family. A real "hustler" lifestyle.
Nowadays we've got everyone working full time for someone else leaving only evenings and weekends to work for ourselves. Or you spend a huge chunk of that salary on childcare, cleaners and dog walkers. We're addicted to work.
This is all feeding wealth directly to the owning class. People used to own a lot more themselves. They used to own clothes that could be repaired; furniture that could be polished, restored and lasted for generations; machines that could be serviced etc. Now nobody has time for any of that stuff. What you "own" is just worthless commodities like IKEA or Zara. Things that used to be assets are just another expense now.
The problem is there's no real way out for individuals. House prices are driven up by couples who both work. Tax systems benefits such couples too. So you're doubly screwed if you want to opt out of building billionaire wealth and instead work for yourself like they used to. Then you've got factors like settlements being built around cars, so now you need two cars, another huge expense (not an asset) or the stay at home parent is basically trapped at home all day. So now you're triply screwed.
What we really need AI for is a way out of these ridiculous local optima we get ourselves into. We desperately need to solve inequality. Unfortunately we also like to feel like we're in control, so any AI has its work cut out: guide humanity to happiness but trick them into thinking it was their idea. I have no idea why an AI would bother to do this for a species that themselves chooses not to do this for other animals and even each other, though.