Would you mind having electronic number plates which promote businesses as you drive?
In California, this may happen in the years to come where vehicles stopped for a certain length of time could have adverts scrolling on 'electric number plates'. These number plates would most certainly display the vehicles registration however only show adverts when the vehicle is not in motion. A great advertising opportunity for the vehicles behind you to notice, as everyone looks at your rear end (number plates).
Factors to be considered could be the costs of bringing these into effect as an electric number plate would most certainly be more expensive if it ever broke down and needed replacing. Whilst metal or acrylic number plates are far cheaper to be made up.
Advertising could also distract drivers from the road ahead, even when the car may not be in motion.