[kobeya]

He may have meant “professional occupations” which means doctors, lawyers, accountants, etc.

[holtalanm]

I know people working for the railroad as track workers that make more than the median salary for a software engineer in my area.

So, take 'professional occupations' with a grain of salt. There are high-paying occupations that don't require a 4-year college degree.

[TheCoelacanth]

Doctors have an extra 4 years of very expensive school plus an extra 3-7 years of training. Lawyers have an extra 3 years of very expensive school and only make about 15% more on average than software developers. Accountants make on average about 30% less than software developers.