Providing a unique identifier of vehicles involved in crimes is not a compelling argument for the state when it comes to crime. Vehicles do not commit crimes. License plates are removable. The state wants their Tax Stamp in plain sight. Even the lowly, parking citation or red light camera, screams that the purpose of license plates is to enhance revenue for the state. Where the state screwed up is when they permitted special designs (to generate more revenue), but denied some groups add space while permitting others.
The annual tax stamp is the inspection sticker and license sticker (now just one) which in Texas is placed in the windshield on the driver’s side.
That same argument could be made for denying letter-number vanity plate combinations as well.