Many Swiss can also babysit and clean houses but it doesn't stop expats doing it too, if the jobs forum is anything to go by. (Besides, just because many can speak it doesn't mean they choose to. I gave birth to my first son in German, which I didn't speak at the time, because the doctor spoke no Spanish, Dutch, French, Danish, or English. Any one of those would have done for me. Same applied to the subsequent three-week stay in hospital.)
Not to worry - you don't have to make excuses, I'm just surprised is all. But then interpreting has always been my dream job (conference though, but that's out of the question now) so I'm biased.