Electronic ads on California license plates?

“Moving billboards.” That’s how some people describe a plan by California officials who want to generate revenue by placing electronic ads on license plates. Here’s how they would work. When parked or stopped for more than four seconds in traffic or at a red light, the plate would display anything from advertising messages to emergency information or Amber Alerts. PopSci.com reporter Clay Dillow observed that “in heavily gridlocked places like California, it could provide a …