Wage

The major reason for a lengthy medical education is to maintain the wage of doctors.

I shall not elaborate here the major determinants of wage for any occupation - suffice to say it depends on the degree of dexterity, extend of physical (and mental) exertion, risk of fluctuation in income, and social position associated with the job.

You may say: That's the point ! Physicians need much mental (and probably physical nowadays) exertion, and we need to be very knowledgeable to achieve the task. The time of a doctor should be better spent in ordering tests, interpreting results, prescribing treatment, and performing procedures - not doing ECGs or typing discharge summaries.

Alas, don't be naive. Do you seriously think fresh graduates from medical school could order sound investigations and prescribe safe (let aside effective) treatment ? It takes some more years of training and experience. Moreover, do you think we need that many doctors if they only have to do the rosy tasks ?

And therefore we need people with five or six years of medical education to do ECG and other simple donkey job. "A long term of apprenticeship restrains (the competition in employment) more indirectly, but as effectually, by increasing the expense of education." (See Adam Smith, The Wealth of Nations, Book I, Chapter X.)

PS. In fact we are heading that direction. Over the years the wage of junior doctors come down a lot - much donkey work is delegated to nurses and paramedics; doctors are given less demanding a task but also a rapidly vanishing degree of freedom to practice independently, and specialty college replaces medical school as the barrier to minimize competition of practising medicine (which is the most effective means to keep the wage high).

But, look, with this argument, the wage is high for (senior) specialists only.