People have been struggling to get enough iodine for a hundred+ years. That’s why it’s added to salt. This isn’t a 21st century problem.
But the point is that Switzerland's environment is especially poor in iodine hence the specific health problems it used to have, and which were much less serious in neighbouring countries.
Link to an academic article discussing how the USA is now in the dangerzone of iodine deficiency.
https://link.springer.com/article/10.1007/s12011-018-1606-5#....