I admit I can't conceive how, manufacturers and producers can continue to produce the amount of product needed to keep all these stores supplied with product.
I remember the day we went to the store to get a quart of milk. Now, look at the milk cases, everything you could think of, coming in all shapes and sizes, and more.
Earl Heier had the grocery store across the street from us on the corner, many years ago. He had everything we needed in his small corner store. I doubt that till we moved in 1943 everything we ate or had in the house came from his store. We bought our groceries at Earls, our drugs, toothpaste and such at a Drug Store, and our clothes, at a clothing store, hardware at a hardware store. What a unique concept that is. I found this old foto on Google, I don't think Earl had carts though, you carried your items to a counter and he would add up your total on an old NCR, National Cash Register machine, made just a few blocks away.