Vitamin B12 is made by bacteria in soil that are important for nitrogen fixation. Animals ingest vitamin B12 because they don't wash their food, we wash our food and therefore any B12 that is in soil.

Meat eaters get second hand B12 that has accumulated in animals, so their requirement is met by eating animal products including dairy and eggs.

Plants don't actually need B12 so there is no B12 in them.

Iodine is something that I choose to get from iodised salt, which is almost supplementation, but I stay clear of all processed foods that have been fortified and supplements. This is also philosophy - I am not an animal. Most livestock gets a smorgasbord of supplements with calories coming from corn, soy or whatever is cheapest.