Quite simple: the reason for this are the considerably lower sales taxes in many parts of the US. This makes it possible to sell slightly cheaper over there. If you live elsewhere, your local tax rate applies, regardless of the currency you pay something in. So unfortunately that wouldn’t change anything.
I don’t understand.. You are German, right? Doesn’t that mean that you only pay tax to Germany, regardless of where the customer lives? Are sales to Americans exempt from German taxation?
Either way, how would one even know what country the buyer lives in? What stops us from using a proxy and paying the American price?