Rick:

I don't think the fact that Australian wants anyone with sales over $75K to collect their GST is preventing the use of their credit cards.

Many US states that charge sales state already require that you collect it regardless of where (in the world) you are based. Very soon this will apply to all states that charge sales tax. The typical threshold is $100K in any given state.

If you have sales to Canada over $30k you are suppose to collect Canada GST. If sales are to one of the provinces that charges sales tax then you are required to collect that as well.

This is just the reality of the modern world with online sales.

As far as I know, no country is forcing the credit card issuers to make sure their sales tax is being collected and/or to deny foreign companies from using locally issued cards.