That may be your experience based on what you shop for and where you do it.

America is way behind Europe on this. 99% of the time I go to Safeway, I have to bring out my calculator because the reference volume/weight is different from the other items on the same shelf.

When I want to buy cherry tomatoes in German REWE, usually half the varieties have their unit price listed in €/100g, while the rest is in €/1kg. While metric does make converting in your head easy, I bet this still throws off a lot of the non-mathematical people and is done very much intentionally.

Safeway and other grocery chains all list price per ounce next to the price.

Interesting, yeah the Safeways I've been to have all had price per ounce pretty consistently.

What is a bit irritating is having to recalculate when items are discounted.

They usually include the price per for the discounted tag also. Only when it’s a buy x get y free is it hard.

Even with in the exact same product but different sizes I seem them use different units to make to hard to figure out which size provides the best value

That seems odd to me. Wouldn’t the store want you to purchase the bigger product, and thus spend more money?

You’d think it would be in their interest to display the per-unit price comparison, to emphasise where a bigger package is better value.

Only if the bigger product is actually the better value, that is not always the case.

I know of several products that the Mid Size packaging has the best Per Unit value.

And several where they are the EXACT same price per unit, so they want to push you to the bigger one hoping you will waste most of it.

Most stores near me make the lettering very small... if you don't have near perfect vision good luck reading the price per ounce.