Of course it's both. In many of these cases, the public has a strong enough interest to justify licensing requirements. E.g., it would be impractical to elimin

Of course it's both. In many of these cases, the public has a strong enough interest to justify licensing requirements. E.g., it would be impractical to eliminate CDLs, licensing for food prep/barbers, etc. Once these licensing requirements exist, it's easier to justify increasing requirements as a way of increasing the barrier to entry.