I've noticed a similar 'this profit margin seems almost vulgar' on the same store shelf.

As you showed with slightly longer zippers.. I notice with car fob remote batteries. An 8 pack is $12 at the store. The same brand, a single will be $5. A 2pack is $7. And the 8pack $12. Do you really need to make $4 on selling me a single? I know shelf space is valuable, but the same store sells things for $1 too on another shelf so apparently <$1 profit shelf space is possible.