Well because Swiss German is vastly different from the German of Germany. I've heard Germans say they have quite a bit of difficulty understanding Swiss German. I've also had Swiss people tell me about speaking English with natives of Germany just to make things easier for both parties. You two must be wonderful linguists.

BTW, Heidi from Mandarin Oriental Munich says hello to you and RichardSF. 3 times in one day, "Hello, my name is Heidi". Wonderful hotel.