Talk about oversimplification! One cannot buy a BMW, Mercedes or Lexus at a Ford or Chevy dealer. Neither at a WalMart.
What I said was: "Virtually no one can compete with them on price, and that's all most people seem to care about these days." I am talking about buying basically the same things at different locations. For instance, you can buy light bulbs at a hardware or at WalMart. You can buy diapers at a drug store or at WalMart. People are willing to put up with long lines, restrictive policies (for instance which credit cards and debit cards you can use), and other inconviences to get the best price. One-stop-shopping is a convenience, but at what cost to the community in the long run?
Admittedly, WalMart had a level playing field when they started out, but now that they have become "The Big Gorilla", that no longer holds true. Why do you think the Congress enacted laws to limit monopolies? To protect small and mid-sized businesses.