You left out murder. Certainly if I believe prostitution laws are against my concept of freedom and they are not uniformally enforced, then I want murder to be legal too.
Conservative doesn't mean being a prig. It means not wanting the Government where it is not the Government's business to be. Especially if the Government punishes some and ignores others for the same offense.
Ok, Mr. Not-a-Prig, ask the gals in Nevada if legalizing prostitution has decreased or increased government intervention in their profession.
But, the reason it's against the law, liberaltarian, is because the Judea Christian beliefs that this country was founded on want to discourage the practice all together.