Comment by dmoy

Accountants have to sit for the CPA exams (four of them), and depending on the state may have required graduate course load. And also you should interview your CPA, because a lot are not very good at whatever specific section of accounting you need (e.g. tax filing).

Plumber is probably the closest to what you're getting at. They are state licensed typically, with varying levels of requirement. But the requirement is often just like "have worked for 2-4 years as a trainee underneath a certified plumber" or whatever. That would be closest to what I'm guessing you would be recommending?

Also relevantly: the accountant and plumber jobs that are paying $300k-$500k+ are very rare. There exist programming jobs that pay what a typical plumber makes, but don't have as many arcane interview hoops to jump through.