Expat Central?

The other day I heard a family around the corner calling out to each other with British accents. Then I passed a house down the street and heard someone say "Oh my God!" in a distincly non-Swiss voice. Two teenagers getting off the tram yesterday could have been at any high school in the U.S. A father and daughter were just walking up the street behind our place talking to each other in clear English. Has my neighborhood had a high concentration of expats all along and I didn't know it? I guess it's not so surprising I'm clueless (beyond my normal every-day cluelessness, that is) since, by and large, if you're walking down the street here and pass someone you don't necessarily say hello (at home we would give at least a cursory "hi" to someone in our neighborhood whether we knew it or not). And if you do say hello to someone, of course you use a local greeting. So far all I know, I've been walking past other expats and not realising it because we either ignore each other or say "grützi". Then again, maybe I should start suspecting that anyone who greets a stranger on the street is actually an expat since it doesn't seem an especially Swiss thing to do.