If you're referring to restaurants, that is because the waitress makes around 4000 CHF per month; if you're referring to food in supermarket that is because the clerk behind the counter gets 25 CHF / hour and not 7 EUR like in Germany.
Processed food like frozen pizza is expensive as a substantial amount of (manual?), well-paid labour goes into convenience food.
I must be misunderstanding something, because these two sentences seem to contradict. In Germany itself, "unprocessed food" is more expensive than in most of the rest of the world.
Sure, in most of the rest of the world food is pcheaper but that compares to even lower income levels.