I'm a label reader but I still get incensed when there is intentional packaging slack. However, in the examples above, both comparisons are using different products. It's common for a specialized product (such as gluten free or high protein) to sell at a price premium (or contents reduction). The unethical illusion still applies, because the naive specialty buyer is duped to thinking it's the same amount of product as the regular version. They dump 12 ounces of pasta into their standard 16 oz recipe and realize it too late.

Another cost to consumers on slack is product damage. Cartons of most dry goods need to be packed snugly so they don't shift/agitate in transit and get damaged. The notion that they are saving money by using a universal package size is absurd with their economies of scale. And they save real money in dimensional weighting whenever they ship/warehouse less air.