You are talking about the people who own Envato Elements site. So do I.
Lol. There are dozens gateways that handle all of this.
If a country force you to pay their taxes for their customers, you just rise your prices for this country. That is how it should work. It shouldn’t be our problem that US or AU have such a law, it’s a problem of those, who live in those countries.
Every business shifts its costs to its customers. That is how it works. Big Mac in McDonalds doesn’t cost the same price in different countries, just because of that.
But the problem is that Envato treat us not like partners, but like their customers too. So they shift some costs of their business to us, instead of rising the price for Americans, or instead of rising the price on Elements and handle all AU taxes on their side, and make us earn fixed 50% from Elements (without any difference in what country do we live).