This information is really interesting for me

The FDA (Food and Drug Administration) not only determined a general “healthy” calorie intake for the average American person, but they also decided to ballpark some upper limits and lower thresholds of certain nutrients, so the percentages you see as %DV (or percent Daily Value) is speaking to what percentage of the recommended daily intake for that particular nutrient it accounts for, not total calories for the whole day.

For example, this bar contains 21g of carbohydrates, shown as 9% Daily Value - the FDA recommends that every adult eat 300g of carbohydrates or fewer per day.