While retailers continue to rely on customers to replace cashiers, their non-payed cashiers will continue to make mistakes. Seems fair to me. Want to reduce your theft? Hire some cashiers. It’s also really stupid to check receipts at the door. It’s irritating to treat all your customers like thieves, plus we know your staff isn’t actually reading the receipts. Retailers might have statistics to show that it deters theft but it also probably deters an amount of sales that they cannot measure.