You ninja'd your comment into something completely different... Responsing to your original comment about MREs: the supply chains for supermarkets already exist. I'd be very surprised if there were enough MREs to feed everyone for a year and then still have the ability to restart normal supply chains from a dead stop.

Regular people shop at supermarkets so they don't starve. Armies carry food supplies so they don't have to shop at local supermarkets. They bring barbers because tight haircuts are essential to military dress and clean shaved faces are critical to tight sealing gas masks.