Actually, fast food and the restaurant industry, in general, was one traditional way that folks with little to no official educations COULD eventually rise through the ranks and earn enough money to not only support a family but to open their own business.
The idea was you started as a bus boy/waitress became a cook/hostess and then worked up to the manager, usually marrying someone in the business along the way. You both saved and scrimped until you could open your own place, often with your kids as unpaid labor in the back.
Early franchises also played on this model pretending to provide "support" to the older idea of "Why don't we open an Italian/Chinese/Diner type place when we have enough money saved?"
I was still waiting tables when I was in Graduate School and there was actually someone who did their thesis on this pattern for an Anthropology degree (not in my school but I read it).
Fast Food worked in a similar way except you started with the part-time cashier jobs, worked up to manager and then district manager; in the early day's places like McDonald's would try to convince people like my very high IQ Cousin to quit college and go to "Hamburger U" to become a professional district manager/head officer person eventually (she declined).
Today that "leg up" into the business is almost gone, especially with the near-death of the small business owner and the extremely high costs of start anything up. These are also the people who have been destroyed by COVID and a lot of them won't be coming back.
Finally, back in the old days (the 1970s) again MEN were expected to be able to support families as waiters, high-end places often ONLY hired MEN as waiting staff and they were well paid and tended to get huge tips - because they had to support a family.
So they tended to get say 4 dollars an hour when the rest of us were getting 2.13 plus sometimes as much as 500 dollars a weekend (that would be like getting about 2,000 a weekend now) in tips, most of which were not really counted or taxed until the late 1970s.
But waitresses, even single Moms didn't get that kind of work (usually) the best they could hope for was a hostess in a fancy place (on salary) manager or the rare lady who could talk her way into cook training. There were many managers that refused to hire women cooks, but there were enough who did that it made sense for skilled and determined women to keep trying.
