Back in the late 60s and 70s, around the time the term "rip-off" entered the vernacular, Ralph Nader spearheaded the movement that put into place many of the consumer protection laws and policies that still survive today.
One of these was the requirement for "unit pricing"- indicating on the grocery shelf price tag the per unit cost of the packaged item in ounces, pounds, etc.
This was enacted to enable consumers to easily determine the cost of a product, since some manufacturers used deceptive packaging to trick purchasers. That 99-cent sale item, for example, might contain only 28 ounces of a product in a box designed to look identical to the 32 ounce box next to it. Divide the price by the number of ounces, however, and you'd discover the "sale" item actually cost several cents more per ounce.
I believe people either have forgotten about unit pricing or have never learned how to use it. Couple that with the almost universal assumption that the larger the package, the lower the unit cost, and it appears companies are again taking advantage of consumers.
Last night I ran out to buy cat litter. I usually get the largest container I can, since our inside feline apparently has the digestive system characteristics of a zebra-noshing wild cat from the Serengeti. Out of habit, I looked at the unit cost of the big containers positioned at eye level- 2.9 cents per ounce- then glanced down at the smaller containers on the shelves near the floor- 2.3 cents per ounce.
Curious, I looked at a number of other items and was surprised to find that about a third of the time, the unit price of the smaller package of an item was actually cheaper than the "large economy" version.
I suspect this isn't unique to the Pittsburgh market. Companies are taking advantage of shoppers' mathematical illiteracy and lack of shopping skills.
Keep your eyes open the next time you're in the supermarket, and do the comparisons yourself. I think you may be surprised at what you find.