Unfunded mandate, privacy concerns, national registry, takeover of traditional state powers, etc.
Now after having read-up on it, it appears that states must tighten their rules on what docs to accept for a drivers license and that the license contain a bar code.
States can opt out of the provisions but then the holder of those licenses can be barred from collecting federal benefits or travel on public conveyence.
I know FL already has tough document standards and a barcode. As opposed to some other states that let any Tom, Dick, Harry, Luis or Achmed to bring their Cracker Jack produced birth certificate and get a license.
There apparently is no Federal db but the states can link their own db together.
Maybe I'm just missing the hype in all this.