The purpose of these types of regulations are to increase the barrier to entry for the poor, usually immigrants or other minorities. You're right that it's a common concept, but let's not pretend that the primary function is anything about consumer protection.
Not always true. I'm guessing the whole racist barrier entry is just one way to abuse these, but I doubt that's their primary function.
Besides, sometimes it's very useful to have certifications. I'd rather get my brain operated on by someone with lots of credentials.
Still, in most cases it's an incumbent industry barrier, nothing more. For example I don't understand why there's a "cosmetology certification". And don't even get me started on the racket that is a "teacher credential"
There is a big difference between wanting service providers with credentials and laws written by lobbyists that require specific credentials offered by a monopoly. Even if such laws/certifications are not corrupt from the start the industry has every incentive to corrupt it and it's just a matter of time.
Kosher food is a great example of private certification.
