Simply put, in the USA if you buy something you've got to pay sales tax.
In Germany/United Kingdom, if you buy something you've got to pay MWSt/VAT.
What I'm trying to say is, as an end-customer you've always got to pay tax.
Incorrect. In the USA, a sales tax isn't a federal tax; it is a state tax that may or may not be imposed on sales of particular goods or services, depending on your state.