Historically, prostitution falls under vice law, and so is written under auspices of morality. Oddly enough, it is not typically discussed when people talk about separation of Church and State, possibly because the liberals of today see prostitution as simple exploitation. Most people feel that selling one's body is simply (ineffably) 'wrong'.

My opinion is that having sex on camera is actually prostitution. But I also don't really care whether prostitution is legal or not - I think it's a rather sad commentary on human existence. It points to serious cultural repression, but it is global.

If prostitution were actually more like the Geisha of feudal Japan is romanticized to have been, a learned and respected art, then it might be ok. Like getting a massage from a trained physical therapist. For something like that to work, though, there has to be a cultural revolution where humanity learns to separate sex from emotion or religious connotation. But at that point, there would be two kinds of sex - professional and personal, as it were. I don't think humanity is quite there, yet.

Joss Wedon's Firefly (http://www.fireflywiki.org/Firefly/HomePage) has a character that is a 'Companion'. In that universe of hundreds of years in the future, she is very much a professional; highly trained, respected, a legitimate and honored practitioner running in the most elite social circles. Some people still call her a whore ;)

Wait ... they pay people to be in porn?!?

Daddy smells a career change ...