Again, you have it wrong.

where nuclear weapons are used so frequently that the average person will need tablets

All it takes is one nuke to go off and winds to carry the fallout to relatively stable countries far away.

But let’s say that you are dealing with some level of societal collapse from nuclear war. You still need iodine. Without it, it won’t matter if you secure food, water, and shelter, because you’ll get some aggressive cancer and die anyways.

Regardless of the specifics, iodine is important.