@helmut_meukel
And Amazon cheated the European booksellers who had to apply their higher local VAT, by pricing books sold by Amazon with the low VAT of Luxemburg.
Makes sense. Thanks for clarifying that.
As to U.S. sales tax, there is no Federal sales tax. But states/counties determine what products will be taxed. So in one state there's a sales tax on clothing but not food. In another state it could be the reverse. In another state both will be taxed. And then there are city sales taxes added to it so if someone were to buy a car, they might go to the neighboring city which has a lower sales tax.
It used to be that to be charged a sales tax the selling company had to have a brick and mortar store in your state. So if I were to buy something mail order from Company A and that company didn't have a presence in my state I didn't pay sales tax. Before Nordstrom's had stores in Arizona, my wife and her friends used to take a weekend trip to San Diego to shop. If they took the items with them, they paid Calif/San Diego sales tax. If the items were shipped to their Arizona address, there was no sales tax.
And then the internet changed everything. States and cities wanted to collect sales tax from their residents so if you buy it online you still pay sales tax.
BTW, Arizona doesn't call it a sales tax. They call it a Transition Privilege Tax (TPT).
ETA: btw, there are federal taxes on products such as gasoline, cigarettes, and alcohol, but that's not a sales tax.