The Coalition Government clearly sees political capital in demonising welfare recipients and appealing to the base prejudices of a large proportion of the electorate.

It's the sort of cynical political tactic that has worked well in the past but one we like to think we've outgrown as a mature democracy. But apparently not.

Of course, the government says the drug-testing plan is not about stigmatising welfare recipients but, rather, identifying people who need help.

And, it would seem, a healthy number of hard-working Australians also like the sound of the plan as a way of ensuring their tax dollars are not wasted on drugs and used to line the pockets of criminals.

But there are two major flaws with the plan that expose it is a nonsense.

The first is the proposal to place welfare recipients who fail drug tests on an "income management" plan that restricts how they can spend their welfare money, or even cutting their payments if they do not agree to a second drug test.

Condemning a troubled person - and, potentially, their family - to greater depths of poverty will not help them, nor the rest of us.

As agencies including the St Vincent de Paul Society and the Australian Council of Social Service have previously argued, cutting welfare payments will do nothing to break the cycle of disadvantage among the nation's most vulnerable.

The second flaw is what the bill does not propose, as highlighted by Senator Jacqui Lambie. Senator Lambie says she will not support the plan until the random drug testing is expanded to include politicians and other public servants on government salaries.

And why not? If, as Social Services Minister Anne Ruston says, "taxpayers expect the government to ensure their money is being spent responsibly", then surely the government would want to prove its own members are not spending their hard-earned on illicit substances.

And if the "if you've got nothing to hide you've got nothing to worry about" argument is good enough for ordinary citizens who resist further government encroachment on their privacy, then it must also be good enough for drug-testing MPs.

It won't ever happen, but how many of us would like to see that?