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.
