Rewind 50 years, and it would be highly typical for a janitor to support a wife and 3 kids on HIS salary - families were larger, and mothers didn't work. The fact that a working single mom can't support her four kids today is indicative in and of itself.

Would that janitor have many vacations too? And decent college funds? Healthcare?

Yes, yes, and yes. Janitorial staff at a Ford plant in ~1965 would make enough to own their own house, vacation once a year (probably not by plane but...), and college was percentage-wise ridiculously cheaper - 30x if my calculations are correct, which they probably aren't, but hey. Healthcare would have unquestionably been provided by their employer. And all that on only a single income for a family of four, no less.

... and with a defined-benefit pension as well, meaning no need for 401k contributions out of their salary, and no risk of losing that money due to poor investment decisions.