Probably the same problem as most health care systems. Regular “general practitioner” doctors like family doctors or what we might call primary care physicians in the US are very much overworked and underpaid.

If you want to make money as a doc, you need to be a specialist at the very least.

I have a family member who is a GP and they said they wouldn’t recommend anyone become a regular doc. Too much work, too much paperwork, difficult schooling, and now nurse practitioners, DOs, and others can write scripts, the GP’s skillset is being undermined and their pay cut as clinics just use nurses to see patients instead of doctors. That’s the US anyway, but I imagine other modern countries’ doctors face too much work and too little monetary incentive to encourage others to want the job.

I think it's mainly because there is a limitation of the amount of students who can start the education. Every year the government holds entry exams and only the best 1600 can start the studies. Somewhere in their studies they have to choose their specialisation (heart, children, oncology,...) And as far as I know only a small part of them is interested to become a 'housedoctor' ( the type of doctor we have to visit when we have something like a flu)