I understand this problem from a completely different angle. I have the greatest honour to be a “master” for 3 apprentices in my personal life. Training them from the point they expressed interest in the craft of programming. It is a very emotionally profitable experience, and would never give up on them. Heck, I even hired one of them as a full time employee. I was well aware what this would mean though. A lot of oversight, 1-on-1s, taking it slow and explaining a lot. Also, letting him fail, and learn from his failures.
That, as a founder is a big investment. It eats up a lot of time and slows production down. But I knew that, and it is fine.
On the other hand, I also have had the opportunity to hire juniors in other settings, where I did not have any say in the way the company was handling them. There, I have seen 2 things.
One is what you’ve described: irrational expectations even though they were specifically hiring juniors.
The second one I found way worse. The intentions are pure, they hire one (or several) juniors and think they new hires will grow under the hands of the seniors in the team. The senior people however already have their hands full, and can’t provide as much attention as they should. Without proper mentoring though, the junior people’s work most likely will be sub-optimal, and cause major headaches later on. This pain generally upsets most senior devs to a point where they move on, leaving only juniors behind, who then become the seniors to the new hires. Can you see where this cycle leads to?
Companies need to be aware that assigning a master to an apprentice is not as easy as making people work together. Some people like coaching others, some get terribly annoyed by it. It could lead to a steady death of the internal culture if this is overlooked.
Bottom line, apprenticeship is good, and more companies should wisely invest in it. Especially that coaching keeps the mentors on their toes, and they too can learn a lot on the way.