Back in the late 2000's when I worked cashier at Wal-Mart in Alberta we did this. There was a threshold, something like 20% difference and it was free. In all

Back in the late 2000's when I worked cashier at Wal-Mart in Alberta we did this. There was a threshold, something like 20% difference and it was free. In all cases the customer was entitled to the lowest advertised price, be that in our flyer or the shelf. Rarely was the issue flyers. Most common cause of mis-marked prices was a stocker not updating the listed price on the shelf. Or an old price tag getting left behind the new price, and thus disappearing. If anything this was a quality check, it gave the store a chance to catch mistakes without burning customers. One source of supposed fraud was price tag printers getting left out. In theory a customer could use the printers to print up their own fake price tags, then request the fake price. Hence lectures from security on never leaving printers on shelf's unattended.