Because when you go to a restaurant to eat, you usually ask the waiter to issue a food receipt when you pay the fee after the meal, so the food receipt is called an invoice. In the past, invoices could be reimbursed, but now the state has cracked down on some lawless elements who use invoices to reimburse meals and waste the country's money. So that some people don't need invoices, the merchants give some discounts to encourage them to come to our store for consumption next time.