I would say that the food is expensive in Switzerland because they want to strengthen their farmers and national food industry.

Switzerland is topographically not really great for farming (high mountains, no big flat areas, not enough warmth), so they have some disadvantages there. All countries surrounding Switzerland are part of the EU, so there are cheap farming products in the shops.

I am living on the border to Switzerland and it is crazy what meat costs in Switzerland compared to Austria. You are not allowed to import much meat, so you have to buy it in Switzerland if you live there.