I'm for bringing it into the open where it can be regulated, policed and controlled. Prostitution is unextinguishable. It should be managed, not ignored. (Ditto drugs, though that's arguably a more difficult problem because it involves more lasting harm.) The way to protect those involved is to take them out of the hands of criminals and let them ply their trade in a safe environment with access to healthcare and security. With that in place, you can then come down heavy on any 'unauthorised' prostitution and pimping.

Question mark over whether this would supply a sufficiency of sex service to meet demand; but those famous market forces we hear about should see to that: lack of supply --> increased price --> more attractive salaries --> more prostitution. Finds its own level.

Not a perfect solution, but progress in the right direction.