Re the Ansett issue and SBs...
From the very article Perspective and yr right are referring to:
CASA recognised the seriousness of the Boeing alert service bulletin. While the US Federal Aviation Administration at that time had not issued an airworthiness directive mandating the alert service bulletin, CASA took action to mandate the service bulletin in Australia. The FAA followed suit.
In other words, the regulatory position was (and remains) precisely as LeadSled has described.