Sorry that doesn’t actually prove that a vegan diet is significantly more difficult to get complete nutrition than a non-vegan diet.

The two mentioned in the block you quoted (calcium and iodine) are often deficient in non-vegan diets as well. According to this analysis only 6 countries in the world meet the daily recommended 1000 mg of calcium per day. Calcium is also present in the easiest changes you can make to your diet (vegan milk in place of cow milk and tofu as a protein). Iodine is difficult to get for any diet, which is why so many jurisdictions put it in salt. It is also usually present in vegan milk.

Regardless, non-vegans tend to be deficient in a totally different subset of nutrients. Both diets need attention in order to get optimal nutrition. On a vegan diet, you need a source of B12, omega 3, and calcium. Most of the other nutrients are covered by commonly fortified foods or are very easy to keep in mind. Non-vegan diets you need to watch for fibre, vitamin D, vitamin E, potassium, magnesium, avoid too much cholesterol, sodium, red meat, and mercury from fish.

Regardless of the diet you choose, you need to put more thought in than the average person in order to have optimal nutrition. Using nutrition to discredit veganism doesn’t work

the science is clear that most vegans have nutritional deficiencies

Source?

From my experience, it takes about the same effort to get a nutritionally complete diet as a vegan as a carnist. The difference tends to be that people compare their current, shitty diet to an unnecessarily restrictive vegan diet.