Walmart operates 1478 stores in the U.S. Perhaps more even more now. Their buying power has to be tremendous. It's virtually impossible for a local merchant to compete so it's really not a question of everyone else ripping you off.

My question is how do you know everyone else is at .67 on Bananas? Reading a circular or spending $2.00 a gallon gas and a lot of time driving around to save a few cents.
I don't have a Walmart near me, I do however have several large Supermarkets, Shop-Rite, A&P, Stop and Shop and Pathmark.
Whenever I have the need to do the shopping, I'm not going to waste my time to go from market to market to save a few cents. My time is worth more than that