People often focus on the wrong things when worrying about ID cards. For me, one of the right things to worry about is price discrimination. Not necessarily the illegal sorts, like redlining, but the legal sorts, in which firms try to sort buyers by their ability to pay, or their intensity of preference. In economic terms, in some cases its an attempt to shift consumer surplus to producer surplus; in other cases it’s an attempt by a local monopolist to move the apparent supply curve. (I’ve discussed aspects of this problem in a number of articles, the most accessible of which is probably DeLong & Froomkin, Speculative Microeconomics for Tomorrow’s Economy.)
For a real-life example of the kind of price discrimination I mean, see Ed Foster’s Gripelog || Dell Has Three Prices For One Part.