Australia is late in the vaccination game due to delay in granting approval and complacency. Initially very few people were infected due to locking the borders early on. However, slowly but surely, similar to other countries such as Taiwan and Thailand which avoided early outbreaks, the virus is now endemic. Zero COVID cases is now impossible, we have to live with it. Vaccinated people with negative tests prior to travel are an acceptable risk. Opening up will result in a slight increase in case numbers, and some people will die but the world can't remain shut out indefinitely.
Fortunately we can study the experiences of other countries which have already opened up and avoid their mistakes. A few months ago, approval ratings for the politicians were running high when COVID was seen as being kept out by strict quarantine requirements, now we have the public rioting while unpopularity grows daily. That might get them to change course.