Do you have price per unit on the price tags in your grocery stores? They have to show that by law in my country, not sure if it makes a huge difference because not everyone knows to compare though.

We do have unit prices, but sometimes they vary the unit from product to product within the same product category, making them useless for comparison. This one is by weight, this one is by volume, this one is by count. At that point you have to do all the math yourself, which most people won't.

I don't know whether that's done intentionally. Hanlon's Razor says to assume not without proof.

Some stores where I live have this, but others don't. And at some stores that do show it, the only reasonable prices are the items that are "on sale". And the sale prices don't have the price per unit, of course.

We do, but not everyone looks at them. I certainly do not always look at it.

A pet peeve of mine is tissues/toilet paper/paper towels. Sometimes the price is "per roll", sometimes it is "per sheets". Sometimes it's even different between different package sizes of the same product. It's infuriating to have to bust out the calculator to figure out if the deal on the 6 pack is a better price than the regular priced 12 pack.