[A1kmm]

The point the article was making was that it is illegal to sell kits which test for levamisole and other harm reduction 'paraphernalia'.

Some people are going to use drugs no matter how dangerous they are perceived to be, and that is why prohibition does not reduce the overall harm drugs cause to society.

Yes it would be better if the externalities of drugs on society could be internalised into the price of the drug - but that doesn't justify government interventions which achieve nothing but stop drug users from protecting themselves against serious harm.