The US labor market only really has shortages by design.
Take my specialty for example. I mostly work on operational multi-modal spatial and sensor analytics at extremely large scales and high velocities (as is typical for these data models). Right now, half the Fortune 500 are trying to hire people that know how to design these systems and throwing silly money at anyone that seems like they can. There is no open source software that can do it and half the required computer science is not in literature, it is an extremely deep technical specialty that takes years of experience to learn. There are, maybe, a half-dozen people in the world right now that know how to design these systems end-to-end from first principles and likely a demand for several hundred. There is no way to manufacture that supply on a time horizon that matters to anyone that wants to hire them.
Even one level lower, high-end systems engineering talent demand is at least an order of magnitude higher than the actual supply. This requires very deep experience to be competent that you can't learn in bootcamp or six months of on-the-job training. Yet despite being paid extremely well even by software engineering standards, as an industry we don't come remotely close to producing enough of them. In fairness, it takes serious devotion to craft and no small amount of talent to become high-end systems engineer -- but few people with the raw talent have that ambition or interest, even though it pays extremely well. You can't force people to do what they have no interest in doing.
PS: People with related skills can always pick up these deep specialty skills with extreme speeds. I have seen someone paid contractor rates to learn a extreme specialty. Including that training, he actually finished the project in less time than the original team had wasted.
It would be like me assuming that I, a broadly competent technical expert, could quickly and easily develop a deep expertise in e.g. high-performance graphics engines. A diagnosis of Dunning-Kruger would not be incorrect were I to make such an assertion.
https://en.m.wikipedia.org/wiki/California_Institute_of_the_...
Look into it’s history and Walt Disney has been training animators for decades. It’s a deep skill that is takes significant time to master, so you need an actual pipeline.
Continuing the idea, NASA trains astronauts. They don’t need very many world wide, but they need a few and the only way to get them is to train these people.
I could go on, but outside of a months to few years for absolutely new fields shortages are by design.
Also, many given the right augmentation tools, the training time for highly skilled jobs may be much shorter.
Doctors(but maybe not neurosuregeons) is such case, because of regulation. Nurses , with some training and tools could replace many.
But this could be true for other professions.
Surpluses and shortages of skilled labor are very unevenly distributed. Differences in ease of automation will magnify this. If there is a demand for 100 neurosurgeons and then cut everyone's hours by 20%, you effectively created a shortage of 25 neurosurgeons. Decreasing hours doesn't increase supply and supply of highly skilled labor is not fungible i.e. you can't trivially retrain a PhD in electrical engineering or truck driver to become a neurosurgeon.
This leads to the following conundrum:
If we forcibly cut hours for everyone across the board then it will create severe supply shortages for the most highly skilled labor that is most difficult to automate, some of which already have severe shortages because it is so difficult to create supply. If we cut hours such that labor supply is proportional to demand then the most highly skilled labor that is most difficult to automate will be required to work by far the most hours, which isn't fair to highly skilled labor and creates a disincentive for required labor.
Systematically reducing working hours may benefit the majority but it creates perverse social and economic dynamics for the highly skilled minority whose labor society can't easily replace.