Many published government reports are also published in 'parliamentary paper' versions (ie. where these volumes have been tabled/presented in the Parliament for the information of members).
If you cannot find a particular report listed on Summon or the Library Catalogue under its individual title, check of a copy is included with the Library's holdings of the relevant parliamentary papers (PP) series - Commonwealth (Australia) or State (eg. NSW).
(Note that prior to the mid- 1990s most reports were only published in print and will not be available online.)