Any State government that wants to broaden the GST should first consider whether the drafting of the GST legislation breaches s.55 of the Constitution, and whether the GST collection mechanism breaches s.82.
There's no excuse for payroll tax on entry-level jobs.
Payroll tax is an indirect tax; it is nominally paid by employers, but "passed on" in three ways:
(i) fewer jobs for the unemployed,
(ii) lower wages for workers, and
(iii) higher prices for consumers.
All three effects are regressive...