A few points. No company actually charges GST they collect it for the government and it is paid to the government on a monthly basis usually.
Overseas companies are not going to spend tens of thousands of dollars collecting money for the Australian government and most of them have said they will not. The Australian government cannot force foreign companies to collect GST.
Australian companies who are registered in Australia must collect GST whether they have an office overseas or not if they do any business in Australia, they are Australian registered.
You cannot force overseas companies to collect GST for tens of thousands of dollars spent of their own money.
The government is not about to outlaw foreign companies who do not collect GST from doing business in Australia.
Online foreign businesses are not actually doing business in Australia so it is up to the importers to pay GST or up to the customs and excise to collect it.
If you look around there are many online foreign companies who will not deliver into Australia now because of this.
