License plates have seen such an enormous mission creep, starting out by enforcing safety inspections and liability for car accidents and finding stolen cars, and continuing down to letting the public and private sectors routinely track motorists' whereabouts.

When license plates were introduced, the technology to make them more privacy-protective didn't exist. Today, it might, but it would be expensive to switch and challenging to get police to give up monitoring powers they've become accustomed to.