We'll come back to them in just a minute.
I suppose supermarkets have always engaged in price wars. As far as I can recall, it started off in a fairly mild way with loss leaders, a small number of products deliberately being sold at a loss in the hope of enticing customers into that chain's stores. In the way of all wars, it escalated from there, through loyalty cards and we have now reached the stage where supermarket chains promise to compare their prices with other chains and to make good the difference if a basket of good could have been bought more cheaply elsewhere.
Sainsbury's do this at the till at the time of purchase, giving a voucher for the difference which can be used next time the customer shops at one of their stores. Asda do it differently. Their customers need to register on the Asda web site and enter the number of the receipt at least three hours after shopping. Any "loss" can be printed off as a coupon to be presented - together with the original till receipt - when next shopping.
(I can only speak for Sainsbury's and Asda as they are the only supermarkets I use.)
And this is where the Wombles come into the story. You see, most Asda customers (me included) really can't be bothered to check the price comparison web site, or they are unaware of the facility. There is at least one man who 'wombles' Asda car parks, picking up till receipts that customers have thrown down. he then uses the price comparison facility and reckons to 'earn' about £2,000 a year claiming money that other folk have left behind.
He says he spends up to seven hours a day 'wombling'. I can think of easier ways to earn two grand a year!