First off, the whole thing is unconstitutional. The government has to have probable cause to drug-test someone. To this point, being poor enough to qualify for government assistance is not a crime. So that's really the end of the argument.

But let's say it's not. Even so, the cost of the testing is astronomical. The field test won't hold up in court, which is where every case that resulted in someone losing benefits would end up. The full-on lab test runs between $50 and $75 a pop.

I'm assuming we're testing people every check, or once a month. So we're now spending a fortune on catching people who smoke weed and bouncing them from the rolls. We aren't catching any hard drug users - cocaine, meth and heroin are out of your system within 72 hours - so we can't flag actual drug addicts and offer rehab for a positive first test. We aren't saving any real money, because of the costs of the tests. And pretty soon we're going to be defending ourselves against a shitload of lawsuits because the law we're working under is pretty clearly unconstitutional and has caused real people actual damages.

Then, after a while, people are simply going to do what they do now - use masking agents for scheduled tests. So we're not catching anyone, but we've managed to fuck up every decent program in the country that helps the poor. But at least we got another chance to blame poor people for our lot in life, which is what really matters!