These are all “professions” that either work directly for the government or use government to limit competition.
A lot of them are also high earners who can see the government taketh away what the government giveth.
I can testify to that. I worked for a midsized engineering firm where the president lobbied hard for an city ordinance to require certain surveys be done or supervised by licensed professional engineers. It was complete overkill for a task that could be competently performed by an unlicensed engineer with two or three years experience in the field. The ordinance passed and the fees charged by "qualified" companies soaked the businesses required to have the surveys conducted.