@usawion @readercat You're welcome! You have little idea of how happy I am to see other people agreeing with me on this point!
As for the source of the misunderstandings, it's actually mostly laziness, primarily by any Americans who don't have much interest in Western history, particularly when it comes to anything "aristocratic." Well, since American culture does not
exactly support having nobility, any disinterest is a little more understandable in that light. I'm also American, so, no, I'm not hating on Americans, just bemoaning the tendency for the opposition to American culture having nobility leading to ignorance, unfounded hatred, and such. Additionally, because in American English, the term "parking valet" is frequently shortened to "valet," anyone ignorant of the term "footman" ends up referring to all male servants as "butlers" — as though it were a general term… So that tendency along with Japanese not having the terminology for a Western setting with some laziness on the part of someone in the translation team or just ignorance plus disinterest, and this is what you get (the ridiculous "personal butler" probably comes from "personal [male] servant").
I haven't gotten around to reading
Black Butler yet (I plan to, along with a
jillion other things), so thank you for the info. I was aware that the series is responsible for the generic name for a butler in Japan being "Sebastian" (in the West, it's more frequently "Jeeves" thanks to
a particular humorous series by P. G. Woodhouse). As for the exact role Sebastian has in the Phantomeve household, I was quite ignorant, so thank you.
Evidently the authors of these works did a very good job!— enough for anyone who doesn't bother to look things up to get confused. (It's kind of like how "Shirley" became a feminine name. Hurrah for the power of literature! [Manga included.])