Honestly, in this day and age in Australia, everyone has to have a MyGov account for government services, so there's really no need for actual polling booths - they could just do the whole thing through MyGov and save millions of dollars. And then the voting could be audited for Shenanigans; Which is probably the real reason they don't do it.
Online voting is an incredibly bad idea. For one thing, it makes electoral fraud at scale way easier - no longer needing boots on the ground means you can flip elections even in deep red areas from the comfort of Google HQ. And the kind of audit you're talking about, where you can associate individual votes with individual voters and persecute them for it - is exactly what the secret ballot is meant to prevent.
Online voting is an incredibly bad idea. For one thing, it makes electoral fraud at scale way easier - no longer needing boots on the ground means you can flip elections even in deep red areas from the comfort of Google HQ. And the kind of audit you're talking about, where you can associate individual votes with individual voters and persecute them for it - is exactly what the secret ballot is meant to prevent.