On the contrary, prostitution is highly regulated in the countries where it is legal.

Hookers have unions, regulations, pay taxes, and are upstanding members of their societies. In Germany, there are even brothels on the side of the freeways with giant neon numbers in the windows. The women in these windows are more regulated than liquor stores... and have better security as well.

Regulation in prostitution is more effective even than regulation in firearms. This is primarily because everyone who wants a prostitute in such societies can find and obtain a legal one. Whereas with firearms, there is always this thriving black market to provide illegal guns to people who can't get legal ones (felons, criminals etc.) The same goes for drugs to a lesser degree. People don't score weed or hash off the street in the Netherlands... why would they when they can go into a nice, legal, regulated establishment and have a joint for the price of a coffee?