In the 1970's a kid straight out of high school could get a job, get married, buy a 3 bed house + garage + car in the suburbs and raise 2.6 children on one paycheck.
Today's third level graduates look forward to a half decade of half-jobs, effective vagrancy, crippling rents, and the growing impossibility of being able to afford even an apartment + car on two salaries.
Compare the lifestyles though. The kid in the 1970's generally didn't care where he lived as long as he got that house (which BTW, was likely MUCH smaller than the average house of today - SQFT per occupant has gone up dramatically in the last ~30 years). Now people just have to live where it's "happening". Nobody wants to live in Boise - it's gotta be the bay area, or Austin, or New York.
And how many of those "third level graduates" were for liberal arts degrees where you're really only equipped to teach what you studied in when you graduate, while 1970's kid in high school took up vocational classes in auto mechanics or HVAC - less glamorous or prestigious but ACTUAL USEFUL SKILLS. Those skills also translate well into being able to do a lot of your own home, auto, or other "around the house" type maintenance saving from having to call a repairman out every time you find a frayed cord. 30 years ago pretty much everyone was decently handy and knew how to fix basic stuff.
And as stated - 1970's kid is doing all this on one salary. His wife/partner/other half is likely at home cooking all of their meals, rather than going downtown for organic artisan tacos and PBR's every night. When you're cooking your food at home you can afford to feed 5-6 people easily for what it would cost for one person to eat out. Now I'm not suggesting that women shouldn't be in the workforce at all (on the contrary I think its better how it is now), but it is a foolish notion to compare two time periods and say that now you NEED two incomes. You don't need it - it's just that now one partner who was once doing very real work to reduce the overhead needed to raise a family is now trading their time for extra income instead.
Honestly, I don't get the mindset of comparing our supposedly rosy past to the present and then suggesting a huge turn towards Socialism as how we return to that. That certainly wasn't the system we had in place back then to get that result.