[dkersten]

I think this makes sense, because C++ is seen as this difficult beast. Non-C++ shops will be impressed that you know any C++, while a C++ shop will want to dig much deeper and make sure you are sufficiently advanced at the language to do the job. Non-C++ shops won't dig as deeply (either because it doesn't seem relevant -- you're not going to be using C++ anyway, so you just need to show programming ability and not C++ mastery -- or the interviewers don't know C++ well enough themselves, since they don't use it in their jobs) and won't ask you about in-depth edge case language features (because why would they if they don't use the language), but in a C++ shop, they will care about all of these things and have people who use C++ and can ask in-depth questions.

Why isn't it the same in Java? I'm not sure, perhaps its because Java has less gotchas as a language (certainly a lot less undefined behaviour and weird memory-related gotchas, no templates, no multiple inheritance etc) and C++ has this "its a difficult language" prestige which Java doesn't have.