FWIW, I don't see how any of that rebuts the idea that VATs and tariffs are both taxes collected at the point of trade and that they can be used for basically all of the same policy purposes (which, as we all know, is not limited to revenue generation).

Yes yes yes, complex rules are complicated. So what? You can do things with a VAT that you can with a tariff, and that you can not with an income tax or estate tax or usage fee or whatever.

They are closely related policy instruments.