A supermarket checker gave me the answer a couple of years ago. For some reason it seemed that the cans were being returned for cash refunds without the presentation of a receipt. (I'm not sure why that is/was allowed.) Those cans of baby formula are extremely expensive. My "baby" is almost 17 and I used to pay over three dollars a can back then.
I have noticed that baby formula is no longer stocked on the shelf; there is usually a sign that ask "ask clerk for assistance."
That makes sense. I thought maybe they were "huffing it". :)
"For some reason it seemed that the cans were being returned for cash refunds without the presentation of a receipt."
Now, that makes sense, because pound for pound it is likely the most expensive non-perishable thing you can buy at a supermarket. Especially the dry kind. It's like a pure protein vitamin packed powder.