You see this complaint a lot with chip bags, which are mostly air.

But chip bags are always mostly air, and can't change, because the air is needed to provide padding that prevents the chips from being ground into dust before you open the bag.

This tends to discredit the genre of "the packaging is there to fool the customer" complaints. If you can't identify when the packaging is critical to the product, why listen to any complaints?

I think that's a known quantity. Only a child would think a bag of chips is completely filled with chips. In fact, I remember first hearing about this in some science show or something; it hadn't occurred to me before then that the bags were mostly empty, it was just the way chips were packaged.

>If you can't identify when the packaging is critical to the product, why listen to any complaints?

But you can identity it. Unless this is your very first time buying the product, you more or less know what its packaging looks like. If you buy a can of soda that's half empty you wouldn't think that it's so the liquid doesn't break.

Also, I've never heard anyone complain about the size of bags of chips relative to their contents. I've heard the explanations, but not the actual complaints. Is that something people actually do?

"Companies don't use packaging to fool consumers" is not something that you can deduce from "some customers are confused about a specific kind of packaging".

And even for chips, "bag of air" isn't the only viable packaging method. Of course others aren't without tradeoffs either.