Funny you mention American English given the fact that a great many Americans have various diacritic marks in their names. You can make the claim that those names are "foreign" but the most common ancestry group in the US is German.
Regardless of the technical arguments, from the perspective of non-programmers, when they see things like the CA DMV being incapabale of doing things as simple as recording a diacritic over a person's name, it doesn't reflect well on the software industry and programmers as a professsion.
> You can make the claim that those names are "foreign" but the most common ancestry group in the US is German.
While true, I think the overwhelming majority of German-Americans anglicized their names several generations ago. For instance, my great-great grandfather switched from Müller to Miller. This is probably less true of more recent arrivals.
Regardless of the technical arguments, from the perspective of non-programmers, when they see things like the CA DMV being incapabale of doing things as simple as recording a diacritic over a person's name, it doesn't reflect well on the software industry and programmers as a professsion.