It's obvious that everything on the list is a store-cupboard staple, not fresh or frozen or from a chill cabinet. If they included perishable items, subject to a use-before date, the whole process would be far more complex and unwieldy.
M&S is not a supermarket. They have only just entered the on-line shopping food market - with Ocado. They don't have the infra-structure for delivering perishable goods.
Best that they stick to what they're good at and can roll out quickly. And, yes, I'd love a quality tin of corned beef or salmon. I could make more than one meal out of those items.