Also, when a bag of potato chips is full of air and air tight, you know the dang thing hasn't been opened. Nitrogen is used in a lot of food services these days. You ought to see the crap we have to go through to sell Nitrogen NF and Oxygen USP as food and medical products.
Blue Bell ice creme is still sold in half gallons down here. I don't care about other makers.
I would bet breakfast cereal makers do this a lot. It seems like the ounce size of those boxes is different every time I go to the store.