I think there's a point at which people simply stop caring about the details and follow their gut. If you were to try to find the best deal for every grocery it

I think there's a point at which people simply stop caring about the details and follow their gut. If you were to try to find the best deal for every grocery item you purchase, you'd spend a lot of time comparing prices per unit/weight, and how available deals affect those prices. People probably rather spend and extra 50 cent and save themselves 5 minutes of comparing numbers on tiny stickers. From that perspective, math skills are irrelevant.