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.
I'll admit that I tend to implicitly trust that the larger boxes on the shelves contain more. I haven't checked the price-per-unit in a bit. Granted, my closest grocery is not a WalMart and I'm typically purchasing mass-produced sundries. Basically, the "Family Size" of Cheez-its is the same at any store.
One thing I have noticed is that 5lb bags of flour/sugar haven't been standard in a hot minute.
FWIW in Switzerland (and surely other places too) you have on the price tag also the price per 100g (or ml or whatever) so you can quickly compare without bothering much with basic maths. Same for online shopping.
And a ridiculously high percentage of the time markdown prices on the shelves at Walmart are not reflected at checkout. Happened to me just this weekend. Walmart, one of the largest companies in the USA, whose job is to sell items, can't do the basics of keeping pricing/signage in sync? BS.
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.