Where I live, a vegan diet is recognised as part of the official dietary recommendations for children, and is provided also in schools and kindergartens: https://www.ruokavirasto.fi/en/themes/healthy-diet/nutrition...
https://www.ruokavirasto.fi/en/themes/healthy-diet/nutrition...
There's far too many stories of babies dying of malnutrition on vegan diets. While it's possible to make them healthier for them, let's not go saying it's recommended, just like children can survive on crappy junk food (and plenty of them sadly have to), provided it's fortified with nutrients for them. There's a difference between surviving and thriving.
And you have given no proof that a child can't thrive on a vegan diet. Surely it's not something a public health authority recommends, because people generally aren't vegan.
I can't find any study supporting that a vegan diet for infants and children can't be as healthy as a non-vegan diet. There are always outliers, but you also have children on non-vegan diets that are missing vitamins and nutrients.
We'll have good data in a decade or so.
Basically the only exception is infant formula, unless the child has a diagnosed milk allergy. There's also a general recommendation against restricted, e.g. macrobiotic and raw diets.
That of course being the rule of thumb, and obviously people don't necessarily build every meal to exactly that pattern. A pizza night every now and then is okay too.
> rarely have any significant nutrient deficiencies
People in the Nordics are usually already supplementing at least vitamin D due to lack of sunlight, and often iodine due to a lack of it in the soil. So in this context, switching to a combined vegan supplement that includes those as well as B12 is a relatively small change.