Even the article you cited contains allusions to the truths I will write about in this comment. "Unequal access to healthcare services and resources", "significant disparities in healthcare outcomes between different regions" and the most hilarious point of all... "Low quality of care". Just lovely.
Let's rid ourselves of all these polite euphemisms though. Here's a likely incomplete list of all the things that you don't see.
What you don't see is the communist president of the worker's party who is literally quoted saying "we need to create a new generation of leftist doctors who accept working for less". Population needs doctors, and they vote, so give them what they want: more doctors. And when you want quantity, then obviously you also want cheap. Flood the market with doctors, open hundreds of new schools with ever more lax filters and bring in doctors from neighboring countries too even though they seem to be in even worse shape than us. Problem solved, look at all those happy voters.
The government's latest move was to remove doctors from the decision making positions that control residencies in an obvious preparation to flood the market with "specialists" by dumbing down the requirements and opening new residency programs, no doubt without any concern for quality. You might be skeptical about this claim but these are people who are stupid enough to believe a nurse with 10 years of job experience is equivalent in knowledge and skill to a doctor. At least one such "illustrious" politician can be directly quoted on that.
There's already a huge number of medics, they just happen to be concentrated in the major cities and capitals. The simple fact is nobody wants to live in some undeveloped shithole. Living in Brazil to begin with is punishment enough, there just aren't many maniacs around here who are willing to work and live in the literal amazon jungle. Even comically high salaries fail to attract doctors to areas like that. Partly because quality of life is abysmal and partly because those little villages are so poor they're actually likely to default on those payments anyway so there's no point. Those are the places where the government wants to ship doctors off to though. You'd think they'd develop the country instead so that people in general would want to move there but that's too difficult. Better to just destroy the profession of the "mercenary" doctors instead until they're so squeezed they have little choice.
You don't see the hundreds of brazilian medical schools soaking up billions in government student loans while providing mediocre education. Student loans are very efficient at making school administrators very wealthy. They were devastating for academic integrity everywhere in the world including the US but this country always manages to make it worse by not even pretending to give a shit about quality. In the US medicine apparently escaped that fate due to stronger regulation. In Brazil? So many of these medical schools do not even have an actual hospital for medical students to practice on. How do you become a doctor without seeing patients? You don't.
You don't see the palpable pessimism in health care workers, as a class. What was once a profession that guaranteed prosperity turned into essentially a joke. Doctors generally do not recommend that their children follow in their footsteps. Why would they want their children to bust ass in medical school just to make six dollars a patient? That's just stupid. And those are the lucky ones. The family medicine workers of the study you cited usually make even less than that. This new generation of doctors is feeling the pressure, meanwhile older generations of doctors are taking the wealth they built up and bootstrapping actual businesses instead.
You don't see the 40 thousand newly minted doctors of dubious quality entering the job market every single year. That obviously brings about difficulties with job and residency availability, not to mention the massive and constant downward pressure on salaries. So how does the typical newly minted doctor react to this adversity? Charlatanism.
You don't see the rampant charlatanism on social media. Social media platforms are absolutely filled with them. "Professionals" promising miracle cures, promising results, just basically doing everything that medical ethics says they can't do. That includes passing themselves off as specialists while having a fraction of the education, or just straight up advertising "specialties" they just made up on the spot.
Hilariously, these charlatans are actually the ones who are making it in this distorted reality. They do things like charge people thousands for aminoacid injections that literally do nothing. Brazilian medicine regressed to literal "blow smoke up people's ass" charlatanism and these people are getting rich off it. Do you know what coffee enemas are good for? I haven't the slightest clue but you bet there are doctors doing that to patients literally right now. Things are so screwed up even non-doctors, people who have never stepped foot in a medical school let alone an operating room, have grown bold enough to do "simple procedures" on their customers.
Ever seen an unemployed doctor? Ever seen doctors become Uber drivers? Cashiers? I have. It used to be a meme. Then it actually started happening. Salary only ever decreases. We have emergency services paying the lowest and ever decreasing salaries. What kind of doctor do you think that's going to attract? The simple fact is there aren't enough hospitals in this country for all of them. Most of the ones we do have are in such disrepair that nobody sane would actually want to work there.
The decentralized public health care system familiy medicine situation is even more precarious. There are workplaces in this country that do not have a working sink for doctors to wash their hands with. You simply cannot exercise your profession with dignity under such conditions. The smarter, better doctors have better options and don't subject themselves to that. The ones manning the public health system are generally the desperate and indebted ones. The ones who weren't good enough to match into a good residency.
You don't see the criminally stupid doctors who fuck up so bad they end up on national television. Doctors working an ER who are so stupid they don't run a simple EKG on a patient with textbook myocardial infarction symptoms. Imagine being this fuckup's lawyer. And it's not an isolated case either, their numbers are increasing. The fact is in Brazil any moron can become a doctor these days and you better believe it shows. The problem with that is people's loved ones die in the process and there's no amount of damages that will bring them back. A few years ago I nearly died of appendicitis myself because they initially blamed my symptoms on COVID19. The doctors who saved my life were all older than the public health system the paper you googled talks about. They're becoming rare now, and knowing that makes me afraid of getting sick again.
I seriously hope you reconsider this "just increase supply" nonsense. I know HN hates doctors and it's kind of a tall order but I sincerely hope what I wrote here makes some impact. Simple solutions like that will not accomplish what you want. To put it mildly.