I see them more as a fingerprint, which yes is unique, but I don't consider providing it when getting my ID to be privacy invading. If that makes sense.

Because what the police is really doing in these cases is that they're trying to identify potential suspects, not find people who have a high chance of some disease to sell them insurances and make money. Because of that I do not find this to be in any way privacy infringing. Just because something _can_ be used in a privacy invading context, doesn't mean that it is in the context being discussed.