[robbrown451]

The key phrase is "where fortification and enrichment have occurred for so long that they’ve become invisible."

That is, if you suddenly stop doing it, you have a problem. In Germany, presumably, they are already finding other ways to get those vitamins.

[sliverstorm]

As I read about the subject, it sounds like they didn't have a good source of those vitamins, as most of the land that makes up Germany is iodine deficient- so even foods supposed to be high in iodine, are not. So the way they found was to iodize their salt.

The information seems to be spotty though.