On Japanese dubs of American movies

I’m sure everyone here is familiar with the trope that Japanese people won’t speak Japanese to Americans or won’t even recognize that an American is speaking Japanese. There’s that famous video of Americans trying to order food in a Japanese restaurant and the waitress claiming she can’t understand them because Japanese people allegedly see Caucasian face and can’t imagine that person speaking Japanese.

I recently saw a clip of the Harry Potter dub into Japanese and it occurred to me that Japanese people must watch American movies and TV shows dubbed into Japanese. We don’t find it odd for Asian people to be speaking English, but do they find it odd for American or British people to be speaking fluent Japanese in movies and on TV? And if not, why doesn’t this transfer into real life?