The new supermarkets used an open plan arrangement, which allowed customers to browse along shelving to select goods for themselves
Today, most supermarkets are run by national or multi-national retail chains like Tesco, Sainsbury's, and Waitrose. They carry a wide range of competitively priced "own brand" as well as branded goods.
There are other supermarkets run by voluntary chains like Alliance and Spar. These also started life in the late fifties when several independent grocery shops realised that they couldn't compete with the big supermarket chains. They organised themselves into groups and used their collective power to bulk buy at a discount from wholesalers. They were then able to pass on the discount to their customers. Although these shops use the name of the group's chain (Spar etc) and sell "own brand" goods they are not owned by the chain. They are privately owned businesses that choose to be part of a collective chain. They do this because if they tried to survive on their own, the costs would be too high for them to compete with larger supermarkets and they would go out of business.