It goes back to the Soviet era promise of full employment in a worker's paradise. Buying something in a shop was a good example. You would ask to examine an article to buy. One shop assistant would take it down from the shelf. If you decided you wanted to buy it, this assistant would give you a chit to take to a cash desk. Here an assistant would take your chit and money and give you a receipt. You would then go to a third assistant hand over the receipt and she would hand it over.