Urinalysis is not the most effective way to detect drugs.There will always a way for determined drug users to get around the tests.Whether it is supplements or using someone else's urine the drug user will get around the test.There are always other ways to test applicants such as blood tests or hair tests.
Right now it's popular to beat up on welfare recipients and blame them for being drug-abusing freeloaders. When Florida tried mandatory drug testing a couple of years ago, they spent tens of millions of dollars on a program that detected tens of thousands of dollars of abuse -- in other words, less than one percent. All that taxpayer money that could have been spent on job creation was squandered in the name of feeling morally superior to poor people. Drug testing welfare recipients isn't worth the time or money.