And what were the Aussie ATC'ers doing when the flight departed radically from its filed route?
From the
report page 3
A few seconds later, ATC observed the aircraft turning left, contrary to the SID, and tracking towards the flight path for the active parallel runway, runway 16L. In response, ATC contacted the crew and requested confirmation that they were tracking via the SID and would be maintaining a heading of 155° before turning right. At the same time ATC held another aircraft in the line-up position for departure from runway 16L
More on the ATC response on page 5.