> Can someone remind me why this fragmented identity system is preferable to a National ID?

States prefer having the power to issue ID cards and all of the control that grants them, they do not want to give up those powers, and politically the states have enough political and legal power to keep it this way.

Don’t make the mistake of presuming that this the result of a flawed cooperative system. It isn’t — it’s adversarial.

Just look at how long states fought to stop Real ID legislation.