I think unit pricing is already law in California, or at least lots of products have a price per unit. It's in smaller text on the price tag on the shelf, not on the items themselves.
(1) of course within limits suitable for our household. It doesn't make sense to buy stuff the won't be consumed before it's getting unusable.
In the very old days in Germany chocolate was only allowed to sold in certain fixed sizes. 100 grams bars had >98% market share, although several other standardized sizes were allowed, too. With EU free markets that regulation had to be abandoned because it hindered free market access. I don't know whether unit price information was introduced at the same point in time, I wasn't living there at that time. But I still hate to see 90 grams and 282 grams chocolate bars where I live now.