Walmarts' color scheme is red, white and blue.

Obviously we all know these colors all ready.  They are the colors of the U.S flag.  The U.S flag symbolizes numerous things, one in particular is trust.  So by using these colors Walmart is trying instill to you that they are a trustworthy company. They may be known for their low prices, but the color scheme they chose definitely helped put them on the map.