Prostitutes don't poison society they are a symptom of a social condition that has been poisoned. If marriage and courting were worthwhile there wouldn't be nearly the market for whores that there is. Labor markets play a role in this too, the more transient and unsettled an area is the more likely there will be unattached males roaming about looking for easy lays. Drug trafficking provides a demand for dark money and drives women to prostitution and is a failure of the state to police or regulate. The price is what the market will bear set by supply and demand.