You mean you can't have lower level people working on bug fixes and small tasks while you save bigger more difficult work for more advanced people? Who says they won't be productive? What is your measure of productivity?

I'm talking about the fact that hiring managers expect applicants to have 100% of the listed skills for any position because their corporations would rather spend money on stock buybacks than employee training.

Maybe this is one area where legislation can help enforce a social norm. Corporate training used to be practiced at prior generations of generations- IBM, GE, HP, etc. With corporate profits at the levels at they are today, Big Tech can afford to spend a little more on expanding internship and training opportunities.

People also used to stay at the same company for 30-40 years.

Personally, when I look for a job, I'm not willing to commit to 30-40 years. I think that part would have to change as well.