Starting next year, most merchants in Germany have to provide a receipt for their customers after a purchase. If you have travelled or lived in other countries, this might be very normal to you. I know quite well the signs in cafes and restaurants in India that say “If you don’t receive a receipt, consider your meal free”.
Providing a receipt is not a legal requirement in India, but it was implemented by merchants themselves in order to avoid stealing from employees, but in Germany, it is a legal requirement. The legislator wants to prevent tax fraud and is hoping that more merchants will record accurate sales numbers, and thus, tax payments will increase.