So, would you require someone to get formal testing before they can code a website for someone for pay? Why?

You have heard of the tech interview process, yes? :-)

Possibly. It could prove that a dev knows what they’re doing. It might even eliminate the need for Leetcode style interview questions.

The parent mentioned regulated professions, but there is a flurry of roles surrounding lawyers, nurses and accountants that don't require certification.

Now, I'm sure there are programs to try to help ex-convicts to get into generic company roles like assistants, data operators etc.

The bar is lower, because we don't need such procedures for was majority of tech positions.