Differences in building standards combined with topological factors.
The other important thing to note is that the rapid intensification that occurred when Debbie was getting fairly close to landfall likely limited the size of the storm surge. If Debbie had hit strong Cat 4 status much earlier and 500km out to sea I'm sure the surge would have been much higher.
We have gotten very lucky with storm surge on most of the major cyclone impacts in Queensland. One day that luck will run out and a major storm surge will hit a major population centre on high tide.
The importance you point to was generated by BOM, what data was available at that
time did not reflect the call as accurate. As my claim and the like comments by others
at the time are simply deductions based on data gathering they hold no weight
when 'arguing' against the BOM call - part of the problem Hanrahan points to.
My take rests on the dithering TC Debbie exhibited as she moved SSW, escalated as the GBR became an 'obstacle' - she was struggling to find the warmer water. That late move due West, coupled with a further slow down, says she was in trouble doing the job under the influence of that ridge AND the GBR - why the GBR is a huge factor in intensity building and so those predicted tide surges touted. Cyclones much further North where the GBR is close to landfall
see limited surge if any, even on much lower core pressures than TC Debbie, and often a shrinking of intesity. I would not discount surge altogether but am of the belief surges of > 1.5metres is fanciful scaremongering, or mathematical largesse.
That said... all indications are these events are going to increase in frequency albeit possibly mostly of the scale of this event and like lesser storms.
So best we get to planning in doing something about that in the way of record and information__ in real time__.
I have posted my 'rant' on that way forward into Page 158 of the topic dedicated to TC Debbie.