I haven't looked into iron fortification, specifically, but the "fortified with Vitamins A & D" is pure bullshit.

The cereals, breads, and dairy are not fortified with Vit A & D. Those are man-made chemicals (produced from irradiated vegetable oils) that "have a molecular structure similar to vitamin A and vitamin D(2)" and, therefore, BigAg has been able to get regulations passed that allows them to call these things Vit A & D, even though they have nothing in common with the real thing (other than a "similar" molecular structure."

My guess would be that the "iron fortified" is probably iron that is mined from the Earth (IOW: rocks), and not the iron that is naturally found in foods.