What happens if prostitution is legal and she doesn't have a business license?
That's a good question.
In my area, we are being invaded by illegal aliens. Lots of them push these stupid little carts around and blow clown horns to sell stale popcorn and cotton candy. Now to my way of thinking, who the hell would buy food off of a cart from an unlicensed illegal? But I see people doing it (none who speak English, though.)
So at first blush I would think, who would frequent a prostitute that didn't have the health certificates and a comfortable place to do business - but who knows with people? Me, I don't really grasp the concept of pornography, it's like watching videos of someone eating a steak or a pie, I can't see the attraction of watching something that you need to be fully engaged in. Yet porn is a billion dollar business, so my tastes don't dictate the guidelines.
Still, legalization would cut out the vast majority of illegal activity and provide some health safeguards for both the hooker and the john.
So what if she didn't have a business license or health certificate? Well the cart pushers have neither and are ignored by law and business enforcement virtually everywhere in California, so I suspect it would be the same, and just ignored.