People don't stop doing things just because they're illegal. You're much better off regulating it and providing support for sex workers than forcing them to work in the shadows, which encourages sex trafficking and pimping. But try getting this into the minds of the "Puritan". They only care about punishment, fantasizing about people they don't like being barbecued for eternity and drooling over people being executed.

Add to that the economic incentives of putting people in private prisons, and you get the largest amount of people guilty of victimless crimes in jail.