Best before dates are a really good idea if you want to reduce the number of food poisonings in a large population. Food is (statistically) very safe before the best before date, assuming proper storage. Most of the time it's still safe well past that date, but you would dramatically increase the number of people who get sick.

It's the same with pasteurized milk. Unpasteurized milk is mostly safe to drink, but occasionally you get really sick. In a large population the difference is noticeable.

Again the same with the much stricter cleanliness rules for restaurants and the like. Usually it's safe to store prepared food without refrigeration for a day, restaurants mustn't. It's also mostly safe to cook on a dirty stove, restaurants mustn't. The difference between your home kitchen and the restaurant is the number of people served.