It couldn't be that ATSB's decisions to investigate are affected by the extent of media interest in accidents, could it?
Seems to be the only reasonable explanation for what they choose to investigate and what not. Apparently if it doesn't make the news it probably didn't happen is the tag line now.
Why is the ATSB not transparent like the NTSB, you can search every submitted accident/incident report here;
https://data.ntsb.gov/Docket/Forms/searchdocket
PS just enter Aviation into the 'mode' field and push submit, it will come up with all the latest.