Most Americans do in fact lack knowledge of German.
Edit: And why don't they look up the transliteration rules before? I mean: I only know few words of Esperanto, but I know the transliteration rules for the letters in the Esperanto alphabet that are not ASCII characters: https://en.wikipedia.org/wiki/Esperanto_orthography#ASCII_tr...
Also see ancestry, there are 50M people of German ancestry in the USA, and only 80M people of Germany ancestry in Germany itself. We're a big enough fraction of the total that if we feel like changing language rules, we have enough people to make it stick, at least as a weird local dialect.
Only if they're sufficiently Americanized (c.f. (a) the kind of Chinese food you get in this country and (b) Anglophones getting really fussy about sportscasters pronouncing Hispanic names using Spanish vowels)
> We're a big enough fraction of the total that if we feel like changing language rules, we have enough people to make it stick, at least as a weird local dialect.
To be able to challenge the language rules, you first have to understand them quite a bit. It is quite a difference between challenging language rules vs. simply not understanding them.
I understand your concern, in German as in most languages words are being homogenized and losing diacritics, first among the youth and informal use, and then even sneaking in to ads and "real" use. It has caused a lot of concern, and a fair amount of pushback, but you can't expect other languages' systems to follow the reactionary rules or care about the internal politics.