Well the answer is simple. I haven't clicked those ingredients yet. If you look at the headings, the second column is only after clicking the reinforced plates. If you have constructors making tons of screws, rods, and plates, you don't really need to worry about iron ore in the to-do list. Your point is very valid, however, if you're still making the miners, constructors and smelters needed to make screws, plates, and rods in such quantities. But to keep things simple when you're at the automated-motor-construction level, detailing iron ore consumption is somewhat unnecessary