Teaching the "missing semester skills" are indeed learned by most people on the job because they are often site specific because everyone is self taught in them, so the cycle continues.
Becoming a senior engineer usually takes lots of on the job experience, one can't really train for it. A PHd helps, but unless it models the same shared industrial scale codebase, there will be gaps in the schooling vs a large engineering org.
One could get a masters (extra year in the US) in the missing semester skills. Learning to refactor could be a 5 credit course. Same thing with testing, could cover property testing, ci/cd pipelines, incremental repeatable builds, fault injection, gradient descent, rollback, fuzz testing, formal methods, proof systems etc. but in a practical way.
It is one thing to know about a skill vs having actually used the skill to solve a problem. It takes years to actually learn how to use Git well. Same for most processes and tools, a formal education in those areas would accelerate the state of the whole industry.
Two things should probably happen. One for early education and second for post hs.
The whole k-12 education system should get more rigorous, front load the early education and get everyone on a rock solid foundation. Like everyone exiting 5th grade can read the international phonetic alphabet and are fluent in a second language at at-least the 2nd grade level.
For post highschool academic education, the credit hours to graduate should be extended or be made variable depending on the degree. Some "hard" science degrees already do this, by declaring 5 credit courses as 3 credits. Still 90 credit hours to complete but the difficulty is much higher. Basically the 4 year degree is now the 5+ year degree. This is ok.
We have or did have a huge commercial market for computer jobs in the "code camp/school" space. All these new participants showed up because there was a huge need for these skills. They mostly teach the missing semester stuff and build a ton of context so they don't get shunned at the new job for the huge gaps in their knowledge.
I think the commercial votec school system does need to get some form of accreditation.
I will not discuss the levels of foolishness by employers in their hiring practices. Utter insanity.