Why do you assume a biometric ID cannot be faked?
Because it's more than a card. It is a veritable system.
The card will contain a fingerprint, photo, and bar-coded iris (eye) characteristics and it will be addressable by swiping, just like a credit card. All employers will be required to use a swiping device, which connects to an ordinary phone line, to identify all employees. ICE agents will be equipped with portable versions of the device -- which can read a fingerprint and an iris.
It is very futuristic, but it will solve the problem of illegal aliens. When they can no longer obtain jobs they won't bother coming here. Those who are here will leave. And those remaining will eventually be detected and arrested.