Before buying anything, make sure the Incoterms are well indicated before clicking Place Order. The DDP is the safest (all duties paid), but any other will get you fees beyond your wildest thoughts.
So, it is not on ST, it is on the international rules and the shipper.
I once purchased from Mikroelektronika (Serbia) while visiting Sweden. DHL delivered as if I was a EU citizen. 2 weeks after, they called me and beg me to pay some fees because they realized that I paid with a canadian credit card, so I wasn't a real EU citizen, and the amount of the invoice was superior to some maximum exemption value. I paid for a simple reason: all deliveries I made during my visit were to my employer, so they sent all invoices to my employer directly (I know, they are stupid, I paid with my personal credit card). If I would have not paid, they would have again and again contacted accounting at my job.