But Australia's constitution gives state governments control over all matters relating to public health. They have the power, and the Federal government cannot override their decisions in this area.
Half of Australia's state governments are Labor governments at the moment (socialist). Throughout the pandemic, they've used their public health power pretty aggressively to exert control over people. If they had their way, we'd probably still be in lockdowns for another couple of months at least. The only way the Federal government could get them to agree to reducing restrictions (and they have - nearly all of Australia is now out of lockdown - there's a few very small lockdowns in one part of the country, but two months ago, about half the country was in lockdown) was to negotiate a national plan that linked opening up to vaccine targets, and part of that negotiation did involve the idea of allowing distinctions between what vaccinated people and unvaccinated people would be allowed to do. Basically, Victoria, which does have a hard left socialist state government lead by a paranoid autocrat named Daniel Andrews (I live in Victoria) forced the situation by being unwilling to agree to anything else, and without universal agreement, we wouldn't have opened up at this point.
Is this justified by any real medical science? I'm not a doctor, but I don't think so. But politics and the constitution meant it's what we've wound up with.
And while it's certainly problematic, even Daniel Andrews is now saying, he wants to remove the different restrictions in the next couple of months. Without the agreement, he wouldn't be doing that. Other states will do it before Victoria - New South Wales, for example, has set a date of 15th December to stop the differentiated treatment and may even do it a little earlier. Victoria, it's more likely to be no earlier than February next year, but it's still faster than it would have been without the compromise agreements.