Very good thread!
Many don't realize the ingenuity and work it takes to run a supermarket.
Even in the 1980's, and early 90's, before labor was leaner, we were still having our people crisp leafy greens and even broccoli in the evenings for the next days sales displays. They were soaked in the large back room sinks in luk warm water to open the cells, then in cold water before being stored in plastic tubs in the walk in coolers overnight.
Some manual in store trimming wrapping was also still being done for cauliflower and broccoli. It came iced in waxed cardboard boxes.
The number of heads designated the size of the produce. 12 size cabbage is larger than 18 size. 24 size iceberg lettuce is larger than 48 size. The higher the number, more per case. Order books stated the sizes so department managers could estimate their sales needs. I still remember item line numbers. Bananas 02550, head lettuce 51411.
On the end of buying for an entire chain, you can imagine the calculating involved when dealing with entire pallets and truck loads. 38 pounds of bananas per case, or 24 hands roughly. 50 cases per pallet.
Then there is the control of shrink, or spoilage. Retail mark up is about 40% over cost for perishables. 50% in the deli depts. Only a one to two percent shrink ratio is profitable per an inventory period of a month, so you can imagine the importance of just on time ordering and delivering logistics.
The profit margins back in the day were under 3%, including overhead of labor, utilities, etc. They are better today, as labor is less costly, and logistics are more efficient.