so... the government is going to legally require us to advertise so they can profit?
Well, I guess technically no, because you can always just not have a car, but it's pretty darn close to legally mandated advertising for everybody.
Plus there are other concerns. If electronic, what about rain? When the teenager who was texting bumps and breaks your license plate in the parking lot and drives off, can you get a ticket for failing to advertise for the government? How long before government propaganda appears on the plates? How long before someone is forced to display an ad that is offensive to them in one way or another?
I'm sure they haven't thought this through; it's a horrible idea that will cause nothing but problems. Try cutting back grossly excessive spending, and giving elected officials pay cuts (after all, aren't they "public servants"?) before you force citizens to advertise for your profit.