I assume, and I may be wrong here, that online companies that ship to Australia already have processes in place to collect and remit GST on goods costing $1,000+. If that is the case, then extending it to the <$1,000 goods should only involve a parameter being changed somewhere in their system.
There may very well be smaller companies that do everything manually and whose business is mostly <$1,000, so they would obviously be impacted. But I am sure that the likes of Amazon has everything automated so I can't see why it would be a big issue for them, other than they lose a competitive advantage. I am sure that is the motivation for their opposition to it.
