Much of the second wave was due to mishandling of the hotel quarantine program. Given the complexity of such operations it was more likely bad luck than mal-intent. It does, however, highlight the problem of using un-vetted privatized staffing for such critical operations, and then under-training them.
Add to those blunders Melbourne's excellent public transport system that everyone depends on, a lack of mandatory mask policy, and you have the perfect storm.
"Department of Health and Human Services epidemiologist Dr Prof Charles Alpren told the inquiry that for Victorians who had developed symptoms over the past month, 1,589 had been genetically sequenced. Of those, 1,577 were linked to the cluster from Rydges, and 12 from Stamford. There were no other genetically linked clusters in Melbourne."
https://www.theguardian.com/world/2020/aug/22/appalling-and-...