If design follows from requirements, the reason for the difference between Aussie packs and US packs becomes clear: the requirements are, for the most part, different. I have not had the pleasure of visiting OZ, but I have followed your posts enough to know that the terrain the denizens of OZ hike in is much less forgiving than over here in La La Land. The vast majority of hiking here is done on (well) maintained trails where the shredding of mesh pockets is not a significant problem and the advantages/benefits of weight savings and convenience become the preeminent design requirements. In spite of the impressions you may have gained by observing our political process from afar, we are not all village idiots and there are reasons, for the most part well thought out, for why we do what we do. Off trail hiking and climbing are another matter entirely, and people who are adept at either have learned, as have you, not to let it all hang out.