But red dye has little to no value to consumers and there are equally viable alternatives. No one is going to start bootlegging red dye 3 if it is banned. Alcohol has huge value and is basically impossible to ban.
What does B12 in alcohol do?
But have those dye alternatives been proven safe assuming an equally rigour test of "well, this might cause cancer but we can't actually prove it"?
If you are asking what would putting B12 (or B1) in alcohol do: prevent serious irreversible deficiencies that are not only horrible for the person themselves, but people as a whole, one way or another.
Call it risk reduction.
B1 and B12 it should be.
As for what that does [1], wet brain.
[1] https://en.wikipedia.org/wiki/Wernicke_encephalopathy
If someone you know is an alcoholic, try and get them to take b vitamins.