The inconsistent logic behind criminalizing prostitution

In George Carlin’s 2001 book Napalm and Silly Putty, Carlin briefly articulated the inconsistency behind criminalizing prostitution:

I don’t understand why prostitution is illegal. Selling is legal, f****** is legal. So, why isn’t it legal to sell f******? Why should it be illegal to sell something that’s legal to give away? I can’t follow the logic. Of all the things you can to do a person, giving them an orgasm is hardly the worst.

Prostitution follows the same logic as organ sales. (Which I discussed here and here). It is legal to donate a kidney–or sex–yet it is illegal to sell any of the two. There are two fundamental problems with this arrangement: First is the blatant inconsistency of prohibiting the sale of something that is legal to give away. The second is the injustice of restricting an individual’s freedom to do what he wishes with his own body.

If an individual voluntarily chooses to sell his kidney to another, and both agree to the exchange free of coercion, the government has no prerogative to intervene. The same applies to sex. If two people agree to trade sex for an agreed price free of coercion, the government again has no prerogative to intervene. In both transactions, no third parties are harmed thus eliminating any justifitcation for government interference.