Different topic. Most of those are commodities that are traded like stocks. On the actual market level where people buy these in stores, the cost fluctuation is minimal.
Milk might have been a better counterargument. Everyone remembers the great milk price plunge.
I understand what you say but it directly affects business that buy those commodities, especially in an inflationary period.
Back in the 70’s we were forced to bid on our aluminum products while raw aluminum prices were changing weekly and often daily. Catalogs were no good. vendors published daily discounts to the catalog prices that became list prices. I really don’t know how we made it through two or three of those years. On top of that, we had to have a guy go gas up our trucks at night when the station served only long standing commercial customers