Customs simply dont have the capacity to check low value items (Under 1,000 AUD) coming in for GST compliance - If they cant get the companies OS to pay it then it doesnt get paid and you wont have to pay it.
FWIW, I used to work for Aus Post when the gov brought this rule in. Both AP and Customs told the gov in no-uncertain terms that they had neither the capacity, not the inclination to collect import GST on the govs behalf. That is why the gov made the big online market places carry the can for collection.
