I did a little research study back in 2003 where I went to various grocers and purchased the same product at these grocers and compared.

Walmart has larger boxes, and less contents, universally, for pretty much everything in a box, and they charge 1/3 more for their 2/3rds of what you get everywhere else. They make nearly 50% more profit from that little slight of hand. And try discussing this with any shoppers and they will say "but the box is bigger", <- actual statement from a CS PhD, demonstrating how it does not matter your education, once outside of that specialization you're an idiot.