Prof,
How exactly are blank lines ineffecient? If the company has got their crewing levels correct (which is what management are paid to do) then blankliners will be worked up to the minimum guaranteed hours, which is what the company pays them. Hours worked = Hours paid. After that, the company can make them work more hours, which gives the company greater flexibility with unforseen flying/sickness/training etc.
As far as SOs on SYD-PER-SYD, they were there because the TOD was over 11 hours, so it's a CASA requirement, nothing to do with the company or the pilots. Domestic have an exemption for this. Not sure why the exemption doesn't apply to longhaul, but London to a brick if the company could have pressured CASA into it, they would have. Anyway, effeciencies and legalities aside, if your family were travelling on a back of the clock sector with pilots doing 11+ hr TODs, would you want the SO there? I know I would.