Alternatively, it points to the economic irrelevance of anything more than a basic education to the majority of the production class.

You don't need to know much to crank a wrench on an assembly line.

Unfortunately, that type of work is slowly but surely migrating elsewhere, leaving a large body of work that DOES require higher education skills. I'd love to see if there was data showing education comparisons through transitions in labor types, say, from farming to manufacturing.