It does confuses me as to why prostitution can be legalised.
There is a distinction between “prostitution” (offering sexual intercourse for pay) and “pimping” (to procure women for the gratification of others' lusts and personal profit).
The article in the original post is about pimping, specifically about the sexual exploitation of vulnerable girls by unscrupulous pimps. Pimping, which is a form of slavery, is mainly related to social inequalities prevailing in a country.
As to prostitution, whatever may be one's personal feelings about it, often very hypocritical, should be the free personal choice of the people involved, and not the business of any state, or of any church, or of anyone else.
Enslaving women, which includes pimping, is accepted (Leviticus 25:44-46), if not prescribed and even enforced (Numbers 31:18) by some religions such as Judaism, as long as the sexual slaves are non-Jews, the “goyim”.
It's funny to note that in countries sold by the media as “dictatorships”, such as Cuba, prostitution is free but pimping is forbidden, while in the US, which sells itself as “the land of the free”, the controlling state brutally interferes with and represses the personal freedom of prostituting oneself, while hypocritically allowing for the social evil of pimping in selected placed such as some Nevada counties.