Having lived for a while in Chile (where according to the article financial literacy is below average), my experience very much agrees with this. I noticed many people struggling with basic arithmetic resulting in me having to check the change at small shops since it would often be wrong. It also leads to people making crazy decisions with respect to choosing to buy in cash or on credit (in quota). I'm not talking about household appliances that people need, but I've seen things like a person buying a 50$ blanket in 12 installments over a year. Many people would just fill up they're salary with monthly credit payments.

I've heard some people say this shouldn't be an issue with most supermarket labels including the "price per unit weight/volume". I agree this should be an obligation by law, but I feel like many people are unaware of these labels. I know it sounds crazy to a tech crowd but I'm sure many people don't compare the weight/volume with the price but instead go for the cheaper product price.