Just a comment as to the roots of the moralistic attitude regarding the buying and selling of sex: I think there were two main variables that made the sex trade so hard to stomach, socially:
One is that sex would often result in pregnancy, and society was not structured or prepared to deal with those children. Society was also not able to deal with the issues surrounding abortion (in the past, licensing something that should be unavailable to married women, de facto breeders that they were, was not an option). Hence, it was easier to "shoot the messenger".
Another is that many serious or fatal diseases were spread via prostitution, and again, society had no way to manage this. Diagnositics were barely existant, much less treatments. Fatherless families and motherless children, plus children deformed or disabled congenitally by their parents... again, it was easier to shoot the messenger.
So society has created one adaption or mal-adaption after another, over the years, to try to suppress the sex trade. Which leads to the question: since both those issues are now fairly easy to address (though not super easy to address), how can society confront those convoluted moral structures, that have now become more of a hindrance than a help?