Regardless, why should a Vietnamese person be forced to restrict their password to ASCII? If you want to sell your devices in a country, the least you can do is to adopt to the local market. I get that Western cultural dominance makes this hard for some, but I think it should be the bare minimum.
I would also argue the counterpoint : why are the local markets adopting things that are barely functional to them?
As a comparison, if all Vietnamese people had three feet and three arms, would they all be walking around with two left and a single right Nike shoe while wearing a Champion shirt with an extra arm thrust through the sleeve?
At what point do customers and users realize they are responsible for giving consent?
because it is common sense