The supplement argument is hilarious to me. The mental gymnastic people go through to justify something they're unwilling to question are insane.
What difference does it make if my B12 was produced by bacteria in a cow's stomach, or by identical bacteria in some factory somewhere? It's less natural? Oh well, I guess meat eaters only eat natural foods then! It's all free range animals that aren't fed anti-biotics or growth horomes, no GMO crops, no pesticides, no artificial fertilizers, no synthetic caffeine etc. Good on you guys.
Come to think about it though, if breeding bacteria is unnatural then animal farming isn't natural either :S
I guess you guys only eat game and fish
There are plenty of places in the world where you simply don't get enough sun, no matter how hard you try. Where there's no enough sunlight to even stimulate production of vitamin D half the year. Gets even worse if you have a darker skin colour. So yes, plenty of people do (or should) take additional vitamin D.