Yea, this is something that's always impressed me about this US. In other countries, I have to pull up a calculator app on my phone, and calculate the price per kg for various packaging sizes, to figure out which one is the best deal. It's almost as though store labels in the US are designed with the discerning consumer in mind...

Don't be too impressed. We only have the price per unit listings, ingredient lists etc. as the result of bad business practices (and sometimes deaths) in the previous century. So it's not retailers or manufacturers responding to consumer demand... they're responding to government laws and regulation.

As most regulations are around the world - a response to some problem. It’s not unique to the US.

Do you have a source for the $/Oz being due to bad behavior? From what I’ve heard it was done purely to address consumer demand.

True enough re: them usually being a response to a problem.

See the 'Background' section on page 11 of https://www.nist.gov/document/sp1181-unit-pricing-guidepdf and more generally https://www.nist.gov/pml/weights-and-measures/laws-and-regul.... So yes, it was done purely to address consumer demand... by way of laws and regulations with producers and retailers under threat of even more onerous laws and regulations.

A contemporary example to hopefully convey the situation back then: if 'right to repair' becomes law at some point, this would also be due to consumer demand. Notice the level of interest companies have in addressing this consumer demand prior to legislation being passed...

It's rarely purely price/oz. Often it's mixed units - eg for granola bars or similar you'll see four different items listed at -

Price/oz

Price/lb

Price/bar

Price/unit (which might be bar or package of two bars)

So you get tk calculate the difference in your head.

Which other countries are you talking about? European countries are, afaik, required to show a comparison price. I'm more surprised there are developed countries that do not require it.

Yes, this is helpful for comparing two items on the shelf next to each other, and it is present in some stores. But there are only a few items that I actually remember the price/oz between visits. Mostly I remember only the price per package (if anything). For example, Triscuits and Wheat Thins are a good buy at $2/pack, and OK at $2.50/pack. But when they shrink the pack, I'm SOL because I have no idea what the price/oz equivalent is.

Maybe this is "my fault", but I'd guess that most consumers don't pay that much attention to the exact number of ounces (which are sometimes fractional) in the box.

I always look for price/weight or price/volume or price/count stickers but many retailers and items only list the price making you do the math.

Even then, I’m aware that many items have differences in content which game the price/measurement like a lower ingredient content (less cocoa per measurement and more fillers or water content).

There is not really a great way to combat these practices if you are not some kind of professional buyer that only purchases at wholesale scales.