Why do Belgian supermarkets not provide price per kg in price labels? [closed]

In most supermarkets and shops in Europe I'm used to see price labels like this:

The only part I usually look at is the price per kg. I thought it was an EU standard, I'm pretty sure it's mandatory in some countries.

In Belgium I noticed that the price tags are extremely obscure, full of weird codes and values (e.g. in Carrefour). Why is that? Is there a way to defend oneself?