Legalize and supervise

Although sex tourism is outlawed in many countries, it continues to grow. "Over a billion served per year"  Totally outlawing prostitution seems impractical.  You simply create more criminals and unemployed Registered, licensed and overseen, it's possible to control drugs, diseases and  wipe out child sex prostitution.  Of course it requires better oversight, that's why there is a registration fee. As of 2014 Thailand was still considered #1 in the industry