What's the deal with the divider?

Here in Belgium going to the grocery store has been quite an experience. First off as an American you are used to saying hello to the cashier, which is met with blank stares. I was informed that Belgians aren't into fake pleasantries which is fine. Give me my groceries bitches is my new line, but the most comical thing about going to the store is the militant precision and use of the grocery dividers. You can be buying one item and the person behind you leaps to put the divider down. I think its every citizens duty and responsibility to stay on top of it. When in Belgium make sure your food doesn't touch my food.