Interestingly, at my local Waitrose, customers can claim the £1 parking fee back if they spend £5 or more. At the self checkout till, there's a little box in which to place the parking voucher when customers click the parking fee icon and the money is deducted from the bill. Clearly people have been touching the icon and deducting the £1 without a valid parking ticket, so now the store has introduced a system whereby an assistant has to be summoned by way of a flashing light, in order that they can validate the parking voucher! The customer doesn't lose any money, they simply lose time, but it goes to show that there are dishonest people all around us all the time.