My biggest worry (apart from the fact that any Australian law enforcement agency or intelligence service could serve the department that released the app with a

My biggest worry (apart from the fact that any Australian law enforcement agency or intelligence service could serve the department that released the app with a notice under the TOLA Act (AA bill) to add a backdoor, and they would be compelled to do it and then deny its existence), is that it probably just won't be extremely effective, but people will see it as a magic bullet out of lockdown. There is a lot of pressure from the right wing and business lobbies to re-open everything, but the only reason that we have had such low numbers is because we locked down early and hard. People are saying "Install the app so we can go back to normal quicker" already - this is dangerous. With commercial grade hardware and software not designed for this, we can't assume the app will be reliable all (or even most) of the time. The period of time somebody is infectious seems to be quite long. So using the app as an excuse to ease lockdown will not work and would probably just result in unrestrained community transmission. Especially as we are coming into winter, we really don't want a second wave!