AT1 FY21 - General Discussion + FA, page-1517

But it does delay finding positive cases by at least half a day best case. It is also not administered as often in quarantine so sometimes cases that become positive in quarantine are missed until after they leave as was the case with the guy from Adelaide who cam back to Melbourne and sparked the last lock-down. Also cases that become infectious are not found early enough to avoid the risk of cross-contamination events in lower grade hotel quarantine.

I am not sure what we can't have both tests used at the appropriate time.

Let's say there were rapid tests done at departure and arrival of international flights. That would find the significantly contagious people and they could be triaged either prior to departure or before they head onto a bus with a driver who can catch it and so forth.

No positives could go to standard quarantine hotels but instead, go to a hospital quarantine with higher standards. PCR tests can be done for all the incoming anyway but we catch the bulk of the infectious cases early. When more travel starts this will be vital as the vaccines don't stop people getting it and it is still communicable but not as much.
High risk workers can be tested more with rapid tests like start and finish of shifts and less often with PCR - say before people have a shift rotation.