Regarding MD incomes: You failed to mention that to become an MD, college degree costs $, varying amounts, even with scholarships given. So, you start the Student Loan cycle of borrowing $. 

Then, after taking review courses ($), the MCAT ($), sometimes more classes ($) and you are fortunate enough to get accepted to medical school. 

OHSU is the 2nd most expensive state medical school in the USA. Graduate Medical Students start their internship and residency training with an average $150,000 debt to receive their medical degrees here in Oregon. 

Next, you move onto a poorly paying, work like incredible hours internship and residency training. 

So, in reality, even when you pay back your student loans from college, medical school, internship and residency, the average MD is steep in debt. So really, it's not the rosie, salary envy job that you think it is.