I don't think software is much different from anything else in this respect. You could learn any job assuming you're fairly intelligent and being taught by somebody decent. In not sure why we churn out degrees now instead of apprenticeships. I assume it's an equilibrium where The quality of people coming out of school is "good enough" that it saves the company money on training.
If you look at it as a way of companies forcing people to pay for their own training, the proper way to bring apprenticeships back is to make college more selective or expensive. This would increase upward mobility for those that can't afford school by forcing companies to train their employees again. However it would probably be seen as an attack on the poor and minorities for making college more exclusive.
Put differently, the increased accessibility of college has killed informal forms of education. To undo this would mean making college elitist again because the widespread nature of college education is what causes companies to hire only graduates.
Another factor in the downfall of apprenticeships is the inability to weed out people unlikely to succeed because of discrimination laws. In the past it was common to get engineering apprenticeships off the street IF you could pass a series of tests. IQ especially has a strong correlation to job success, and only taking say the top 10% of scores made apprenticeships much more likely to succeed (and less expensive for the company). These tests were found to be biased against minorities and women so disappeared in the 60's, around the same time college education became popular among the middle class.
Correlation isn't causation of course, so I can only speculate on these being driving forces behind the end of job training. Looking back at Germany, an interesting twist is that education is free but the acceptance rate low. Basically college in Germany is elitist, and if my theory holds water this would lead to more on the job training.
Another somewhat depressing thing to keep in mind is that HN is a bubble. You need to be fairly smart to be an effective engineer. Most are significantly smarter than the average person, and by popular accounts an odd bunch. It might seem reasonable to people like us to teach people to code by osmosis but to most people programming is incomprehensible and unenjoyable. I saw this first hand in primary school where software programming was an elective. There were 30 or so students in the class and only three of us had any idea what we were doing and interest in writing code.