Yes you're absolutely correct. I for example can't use my bank card on the US eshop, it asks me for a Zip code and recognises my payment card is not in the US. It's weird because the 3ds allowed you to make purchases still.
There seems to be mixed verdicts on which cards work where. Some guys in the US can use their card in Mexico for example.
UK cards defintely work on the South Africa store for example, and it's actually cheaper than buying from the US store as the pound is much stronger than the Rand.