This idea was tried before, but for just a subset of the population, though:
Like it or not we all have piles of metadata that follow us around. A big one is our face. It won't take long for facial recognition to do the same thing I mentioned in the previous post; except you won't have a choice then. Hell, you won't even know.
The metadata badge idea was of course not serious; but it doesn't seem so farfetched to me or absolutely terrible. It (as I proposed it), at least, would be something you controlled.
Which, unlike state IDs, licenses or Nazi' camp badges are not something you would control.
I do not appreciate the extreme association with a free-thought idea to that of the worst massacre in history. I'll assume you meant no harm, but still - I figured I had to at least express clarification.