Many states oppose national ID drivers' licenses.

Remember that time when Congress passed a law that tried to create a national database of drivers' information and turn drivers' licenses into national identification cards? And remember how groups from across the political spectrum joined forces to tell Congress, the president, and their state lawmakers that they objected to this law, known as Real ID, calling it an unfunded mandate that trampled on states' rights, decrying its lack of sufficient protections and potential to increase racial discrimination, worrying about its negative impact on the Amish and other religious denominations, fretting that it would create an expansive and cumbersome new bureaucracy or facilitate the tracking of individuals? Opposition to Real ID united everyone from the National Governors Association to the ACLU to the American Conservative Union, the Mexican American Legal Defense and Educational Fund and National Organization for Women to Gun Owners of America, to name a few.

If you've been fishing in your pocket trying to find your national ID card, stop. Twenty-five states, either through statute or legislative resolution, rejected the act or said they would not comply with Real ID, and 15 states have laws prohibiting compliance with Real ID. Since the federal government's only recourse under the statute would be to bar citizens of those states from using their drivers' licenses to enter federal buildings or board airplanes, which would bring air travel to a grinding halt, Real ID implementation has been delayed and delayed and delayed and delayed. In fact, the Department of Homeland Security, in whose jurisdiction Real ID falls, only has four full-time staffers working on its implementation.
http://www.aclu.org/blog/technology-and-liberty/yes-states-really-reject-real-id