No – most people who receive income support do not use illicit drugs, and there is no evidence that receiving income support is a cause of drug dependency or use.
For example, according to the 2013 Australian Institute of Health and Welfare National Drug Strategy Household Survey, less than 6% of unemployed persons had used methamphetamines recently and 90 % had never used them. (Methamphetamine usage is one of the major targets of the trial.)
If this trial goes ahead, most people tested will never have used hard drugs. We already know that many of the processes people need to go through to receive income support are unnecessarily onerous and deliberately difficult. This trial will add a new layer of stigma for people struggling to find employment.