I was at my local Walmart today, in Toronto, Canada. Two customers in front of me was an elderly woman who had, in her cart a variety of soft goods items such as a small rug, a shirt, some toothpaste, but also some groceries such as eggs, and a 4L bag of milk. Unfortunately her credit card was denied, so she left her products at the checkout and walked away.
The Walmart staff then said that all grocery items she had touched were to be disposed of and not returned to the shelves. These items were in perfect condition and had never left the store. I was a bit shocked at the lack of thinking behind their actions. It takes a lot of energy to create and process something like milk and eggs, and to see it wasted is sad indeed.
This situation happens regularly at my local big box grocery stores, and I am positive they simply return products to the shelves.
I tried to contact Walmart Canada through their web site, but they have no means to do this.