mark46th:
I think it's more of a "Why is DHS lying to us again?" issue, rather than a privacy/4th-Amendment issue.
This, especially after that Maryland transit cop stopped a Florida driver just because he thought there was a firearm in the vehicle, after comparing the guy's license plate/DL to some database where his CCW was listed (thus, escalating it into a 4th Amendment issue).
Cross-thread points
Also, it's far more common to carry a drivers license than a passport when you aren't leaving the country.