Buyer question regarding items shipped internationally…

Wondering if any Amazon Sellers can help clarify this for me, thanks in advance…

So I bought an item through Amazon recently from a 3rd party seller that ended up shipping from Hong Kong via DHL. Nowhere on the product page or anywhere in the purchasing process did it indicate it would ship from Hong Kong, and I was charged my local state sales tax. In fact I specifically ordered through Amazon and paid a higher price for the item rather than buying from a site like AliExpress or Banggood because I wanted to avoid import duty fees and tariffs and whatnot.

Yesterday I got a call from DHL saying there was a hold duty that needed to be paid before delivery. My impression from reading the A-Z Guarantee terms (specifically #6) is that the seller is supposed to cover all of the international shipment costs. Is this understanding correct?

I noticed the seller also sent me a message yesterday in rather stilted English saying I needed to pay the tax on the item, although the way they phrased it, it sounded like the wanted me to pay THEM the tax? Unclear, English was obviously not their first language.

What I’m wondering, assuming that my understanding of the A-Z terms is correct and the seller should have sent the package Delivery Duty Paid, is if this seller simply isn’t aware that they are supposed to be covering all of the international shipping costs when selling through Amazon, or if perhaps they ARE aware, but are sending items out Delivery Duty Unpaid and trying to stick the buyer with the import duties.

Hopefully I’m explaining this clearly, I’m rather confused as I’ve never encountered this before, and the current constantly shifting tariff situation also adds to the confusion, although as far as I can tell from DHL, these are not tariffs I’m being asked to pay, but rather customs fees / import duty / etc. (not sure if I’m using the right terminology)

Any help understanding how this is actually supposed to work would be much appreciated, thanks!