Basically, the med schools want to bring in more students which will, in turn, create more doctors. Existing doctors see this as competition and a threat to their livelihood. They are already well paid in Korea, so it’s just the doctors being greedy. What country wouldn’t want more medical professionals?

in the medical field you have sort of two opposing forces:

there’s a severe lack of personnel, because personnel is very hard to train, and its not practical for doctors to train a bunch of people simultaneously.

Governments want them to train more, but the consequence of training more is you get sloppier work, and all the doctors pay will decrease because theyd essentially be training their competition/replacements.

Given the fact that the medical field is one of the hardest fields to enter (and one of the costliest ones), existing doctors have much more to lose if there is a flood of new workers. Doctors on a reletive scale are overworked and underpaid, and adding more staff would address the overworked part, but doesn’t fixed the underpaid part. Given that South Korea has a socialized health care, it’s virtually a matter of the government willing to pay more for doctors or not

edit: I should preface, by underpaid, its not how much they get paid once they finish all their trianing (which is a lot, almost 4x the average). it’s just that while doctors are going through the intern status, they get paid peanuts(basically country average) while working (an illegal) amount of time, so the journey up to becoming a full fledged doctor is basically work slavery. It’s in a very similar boat to like trade school apprenticeship (where you start off with destitute pay) but gradually gets better and you get options for more hours. the only difference is doctors have that mandatory almost decade year of training while trade jobs start work almost instantly.

There are a lot of problems in the Korean medical system. Here’s a journal report discussing a few of the key points: www.thelancet.com/journals/lancet/…/fulltext

Here’s a longer article going into detail why the residents are so upset.

Basically, there are a lot of problems with the South Korean healthcare system, leading to unsafe public health situations. Instead of actually trying to fix any of the problems, the government decided to significantly increase the number of residents each year (throw more people at the problems), criminally prosecute them for mistakes, and also tell them it might be illegal to quit, so they’ll just take their whole medical license away. Like 90% quit and said they’re not coming back. There was a suggestion that the government, instead of completely revoking resigning residents’ medical licenses, may remove their ability to work in hospitals ever again, but allow them to work in rural clinics because they’re already so understaffed and no one wants to live in the middle of nowhere for shit pay… unless the only other option is to find a new field of work and waste all those years of med school.

*Edited to add more context