If you’re suggesting you can get enough b12 purely through a diet without animal products, supplements or fortified food you’ve misunderstood nutritional science.
What I’m railing against is this; vegans say that omnivores eat meat only for taste pleasure and that’s a straw man argument.
No one just eats meat for taste because there is also a nutritional component. In the same way vegans have to supplement with B12 to be healthy so they recognise that things must be eaten beyond just taste pleasure.