When technology reaches the point where we can have a reliable biometric ID system, which is tied to an easily accessible database containing limited info (just enough to actually tell people apart), and which therefore wouldn't require carrying any cards, or provide the opportunity for forged cards to be used, then I want it immediately. Because until we have that, my vote is being diluted by all sorts of fraudulent votes from illegal aliens and multiple-vote casters, and my economy is being trashed by endless illegal alien workers and endless scam artists, and my security is being compromised by all sorts of dangerous unidentifiable people (terrorists, violent criminals, etc.) living in our midst and interacting with us and our families. I don't need freedom from being identified badly enough to give up my vote, my financial freedom, and my physical freedom.
Biometric data cannot be kept secret, nor can it be changed if compromised. It is only useful in situations where everyone who has, or can claim to have, scanning apparatus is trustworthy. For something like the entrance to Fort Knox, this is a reasonable assumption. For something like making credit purchases, it is not.