If you make something illegal you make it hard to control and monitor
Sex traficking skyrockets, drug abuse, physical abuse and so on
If you make it legal, as a buisness that pays tax. Workers there are protected by law and medical care, cash goes into tax for the state, there is less abuse bcs it is legal, traficking drops because you no longer need to force women to do it illegaly.
There will always be prostitution, always, the question is why should criminals benefit from it and not thw state?
Look at prohibition, perfecr example od what happsns when you ban something