Earlier quoted context omitted.
For an example of unionization and certification issues that deal with this, look at the medical field. There are many more people that want to be doctors than there are spots in med schools (US-centric view point here). The AMA artificially keeps the enrollment numbers at med-schools low, so as to drive demand for doctors in general and therefore, increase their wages. The AMA is well aware of the current shortage o…
A more accurate term for what is 'required' is a Guild. Medicine and Law are the last two examples in the US. It is a crime to practice law or medicine without a license. And, for the most part, the amount of licenses dispensed each year is left up to the practitioners' professional association. In short, you'd want to make it illegal to program for pay (or to distribute free software) without being a member of the g…
Bridges don't just get designed and built. A PE is usually required to sign off that these structures are safe and usable. Little Fischer-Price playhouses aren't the same as the Tacoma Narrows Bridge. Though not a guild in all but name, the PE acts just the same.
In fact, there is guild-like behavior in a lot of professions, come to think of it.