If you didn't complete high school that means you joined the labor force instead. You are right that of those who went to college, it perhaps wasn't those with connections to the working class economy and readily available local blue collar job opportunities. That being said, if you didn't want to work with Dad on the factory line at 16, then you just hit the books, graduated, and were virtually guaranteed college admission if you simply completed high school.
People weren't completing high school back then because it was a difficult or a privileged thing to do, they didn't complete high school because they didn't need to complete high school in order to land a job paying a living wage and start a family. For decades, a year of college was something you could pay for with a summertime of part time work, it was not reserved for the rich and elite, but those who simply wanted to go to college.
Now we've structured our economy such that if you want a living wage or a career you can grow, you do need to go to college, and not just any college but a good one, and sometimes more school afterwards. The economic incentives are not the same. For instance, the GI bill was invented to reintegrate returning veterans right back into their life plans when they returned from WWII with little difficulty. Today, the GI bill is used by many as a way to pay for college in the first place, not as a restitution payment for being conscripted to military service like it was after WWII. College is so necessary these days that people are willing to risk a deployment to a warzone to get this scrap of paper, but this wasn't always the case.
I think a lot of the people choosing to forgo education for an immediate job probably also had some familiar financial pressures that made that choice more appealing. Children helping their parents with money isn't new; the expectation of 12+ years of schooling is new.
Choosing to continue formal education rather than generate income is a choice that is a lot easier for those who are better off. It's surprising to me that, even as vaguely leftist sentiments run through it, your argument hinges on a myth of egalitarian education while denying any possible effect of wealth inequality.
People weren't completing high school back then because it was a difficult or a privileged thing to do, they didn't complete high school because they didn't need to complete high school in order to land a job paying a living wage and start a family. For decades, a year of college was something you could pay for with a summertime of part time work, it was not reserved for the rich and elite, but those who simply wanted to go to college.
Now we've structured our economy such that if you want a living wage or a career you can grow, you do need to go to college, and not just any college but a good one, and sometimes more school afterwards. The economic incentives are not the same. For instance, the GI bill was invented to reintegrate returning veterans right back into their life plans when they returned from WWII with little difficulty. Today, the GI bill is used by many as a way to pay for college in the first place, not as a restitution payment for being conscripted to military service like it was after WWII. College is so necessary these days that people are willing to risk a deployment to a warzone to get this scrap of paper, but this wasn't always the case.