That is a good point that may offset to some extent. From the glimpses I've had of grocery store stocking - especially when it comes to produce - I think Costco

That is a good point that may offset to some extent. From the glimpses I've had of grocery store stocking - especially when it comes to produce - I think Costco is still more packaging-per-volume for the things I buy. Costco also still has an additional third layer of boxing for most items between the sellable packaging and the pallet. For example the boxes of tomatoes I mentioned are additionally housed in a 6-unit box and it's those boxes that are stacked on the pallets. I supposed the final outcome depends on what one buys - processed/frozen food probably has a better packaging efficiency at Costco.