What makes Surprisingly Good Foreign Language surprising?

Most examples on Surprisingly Good Foreign Language are just "this language is portrayed accurately". That isn't really a trope, and "surprising" is subjective. The description even states that it's based on how the viewers react to the language portrayal.

It seems to be operating under the premise that Gratuitous Foreign Language is the default, which would make accurate portrayals of a foreign language rare and surprising whenever they show up.

I don't know how true that premise is though which does call into question this trope not being YMMV