The entire mentality behind this is just a heavy handed take on the misguided notion that using drugs (but really only SOME drugs) is somehow immoral and must be punished. Don't forget, this does not simply weed out addicts, it targets casual drug users as well. Don't forget that a THIRD OF THE COUNTRY have, at some point in their lives, used marijuana. Most drug users, even impoverished ones, are not dangerous addicts, they're simply people who like to feel good once in a while. And people in poverty are the ones who most need an artificial way to feel good.
This is just a lot of bullsh*t moralizing, and the continued attack on the poor.