Unfair trading

Having spent over a decade working with adults who have disabilities I'm particularly sensitive to anything which disadvantages them. I wanted to buy some Branston baked beans last week. Tesco had a four pack (I only wanted two) For £2.57, while single tins were just 50p. The mental arithmetic is simple for me, but not so for people with learning difficulties, which is generally accompanied by a limited income. Two days later, lidl were selling four packs for £1.87. With a car and the means to buy fuel, cherry picking products from supermarkets isn't a problem for me, as it generally is for people with learning disabities - do other members feel that innumeracy is exploited by supermarkets.