Yet wages have remained flat or dropped.
Family income has increased in many families because now there are two workers per family.
So, what these statistics are actually saying is that, for middle class families, two people working together are now making only 29% more than a single person was making back in the late 1960s…
Also, in the late 1960, the average number of hours than a person worked per week was about 41 hours. Nowadays it is over 45 hours.
So, for something like 150% to more than 200% more work time, families are now making 29% more money than they did in 1968.
Of course that means that the fact that families have two cars is not because of increased prosperity, but because that is a basic requirement, since families have two people going to work. That also means higher expenses for childcare, which the authors of the report seem to ignore as well. Of course, health care has become a lot more expensive, more so than inflation.
So people are working many more hours for not much more money, and a lot of that money goes to compensate for the fact that they need to work those hours. That is not an increase in prosperity, and not a realistic increase in income.
If the income that families have today were the result of having one working adult per household, AND that person was working the same hours as in 1968, AND the expenses per household were the same, in THAT case, families would be better off today than they were in 1968.
Basically, when they adjust for inflation, they do not adjust for the extra expenses incurred by having two parents working.
A family whose income is in most of the mid income deciles in the USA has a quality of life equal or lower than that of a person of the same decile in 1968. Only people in the top deciles have a better quality of life, though many people there are working many more hours than they did in the 1960s as well.
Only in families for which childcare and healthcare expenses are not a large part of their income have seen a real income increase. Since those expanses tend to be a lot flatter than everything else, that means, as usual, the only people who have actually enjoyed a real increase in income, are the people at the top. It also explains why their share of the accumulated wealth in the USA has increase - unlike the rest of the country, they now have even more money to save and invest.