I cannot find any evidence that the 2005 "law change" was anything more than a rumor (nothing I found specified Corvettes either). The latest Illinois Rules of the Road publication says this:
License Plates/Registration
Most vehicles are required to have two license plates. License plate frames should not cover any of the information on the license plates. License plates covers are not allowed.
- Passenger vehicles, trucks and vans must display two plates, one on the front and one on the rear.
- When a vehicle is sold, the license plates should be removed and kept by the seller. In Illinois, license plates remain with the owner, not the vehicle.
- Motorcycles, motorized pedalcycles, trailers, semitrailers and buses registered under the apportionment provisions display one license plate on the rear of the vehicle.
- Truck-tractors and apportioned straight trucks have one license plate on the front of the vehicle.
When you receive your license plates and/or sticker, you also will receive a vehicle registration ID card. This should be carried in your vehicle or with you when you are driving.
Its basically an EXPENSE that each individual state justifies or not, I guess. Oh well.