If you eat meat from industry chances are that your b12 vitamin comes from supplements. B12 supplement is very very cheap and everyone should supplement.
Secondly, I'm not sure what your first statement is intended to mean. When I eat meat, it's from usually chickens, turkeys, some fish, crustaceans, and occasionally western pig and cow (and even more occasionally, game animals).
As always, it's something each person should go over with their doctor—especially vegans or vegetarians who don't want to begin (or return to) eating meat.
B12 is synthesized by bacteria, algae and yeasts, not directly by the animals we eat. There's a theory that due to the conditions that most animals are farmed in nowadays - the environment and standardized and monotonous feed - they would be B12-deficient themselves if not for supplementation.
So most of the B12 you find in factory-farmed animals might be from supplements in animal feed. Just like how farmed salmon and eggs have a nice color because of supplementation. Check this out: https://nutrition.basf.com/global/en/animal-nutrition/use-ar...
That may be, but the mechanism through which B12 is absorbed in humans is the same whether or not the animal received a supplement or not. It's the process of uptake through the diet that is the part that is concerning to humans.
More simply, the mechanisms involved in uptake by eating beef that received a B12 supplement is still very different from directly supplementing so the comparison should never be drawn.
As an aside: I would be skeptical of any chemical company's recommendations to the agricultural industry at large...
