So, here goes my Tesco analysis:
1) I am always in two minds about Tesco, as despite the fact that I am all for local economy, Tesco essentially paid my rent throughout my degree. This is primarily because my father works for Tesco as a computer system's designer, and has done since I can remember (wine website is his baby, as are a good deal of the pay at pump petrol things: not the actual system, but behind the scenes bits and bobs).
2) Tesco is one of Britain's primary business successes, it not only has national profile, but international profile in: Korea, Japan, Eastern Europe, Ireland, US. It is currently the world's third largest supermarket, behind Walmart (which leaves the rest of them standing in terms of profits) and Carrefour.
BUT
3) supermarkets lower consumer expectations: whereas we used to pay more for food, in terms of division of wages, a far lower proportion is now spent on groceries. Part of this is because of the mass-produced food we now eat, but part of it is the way they treat farmers. For the most part, farmers are treated atrociously by supermarket chains, even organic farmers. This isn't due to evil, per se, but is an outcome of the capitalist system.
4) Supermarkets have had a tendency to wipe out local business, especially the high street food shops. Again, this isn't primarily the supermarket's fault, but is part and parcel of changing work/life balances etc.
As it is, the supermarket is more of a symptom of the problems of our way of living than the cause of the problems.