Except, for many things buying less frequently results in less packaging, fewer trips to the store, more economical purchases, etc. Lots of upsides to buy once, store for a while.
While bigger packages could have thicker packaging, that's not always true: packaging that protects from the outside world won't be any different. A foil layer is a foil layer.
But you have to consider the packaging that you don't see at other retailers: it might come to them in the same packaging, but it's discarded before you see it.