YES to all of this. I am bilingual and well into my 30s and I still get asked to "say something" in my native language. I travel a lot all over the world but this type of request only ever comes from Americans. It drives me crazy. It serves no purpose other than, as you said, performing for the asker and allowing them to develop a superficial view of how the language sounds, as opposed to translating something more specific for them, which at least could be informative if they were to retain the information.