As far as I know Tesco has never been linked with unethical work practices... but that is in the UK, they might behave very differently in the US. A member of my family works for Tesco in it's distribution chain: Tesco bought out the distribution chain company last year, and his wage and work conditions rose considerably as a result.
I dont buy the idea that somehow local shops, who are not specialized enough to survive generalized competiton from big supermarkets, have some special right to survive... that's nonsense unless you subscribe to some kind of communist view of the world. No-one has a right to run a shop, if you cant make a job of running your shop, go work for Tesco.
I can maybe understand the nostalgics who just think something is better because it's 'how we used to do things'. I can understand them, but I dont agree with them. I get annoyed with people who want to force me to have to travel to small high streets with inconvenient parking, moving from shop to shop to try to find what I want - a pointless waste of my time when I could do it all faster, easier and quite possibly cheaper at a successful supermarket. If someone establishes a useful business that serves its customers well, they should be rewarded with success. The only place a line needs to be drawn is at monopoly.