The cover deal is a fine line and can be a slippy slope.aren't they risking...
Indiana Code 9-18.1-4-4. Display of license plates; violation
(b) A license plate shall be:
(1) securely fastened, in a horizontal and upright position that displays the registration expiration year in the upper right corner, to the vehicle for which the plate is issued:
(A) to prevent the license plate from swinging;
(B) at a height of at least twelve (12) inches from the ground, measuring from the bottom of the license plate; and
(C) in a place and position that are clearly visible;
(2) maintained free from foreign materials and in a condition to be clearly legible; and
(3) not obstructed or obscured by tires, bumpers, accessories, or other opaque objects.
https://www.buyradardetectors.com/blog/2019/03/state-license-plate-laws.html
Like it has been posted you see covers all the time and makes you think it is okay but most of the time really not as people are just lucky or exempt from being pulled over.
Had one friend have a cover over his plate as he is a collector and every year would get a new plate so he had a clear cover over it so it would be kept clean and nice. Was pulled over and given a ticket for obstructing the plate and had to remove it one the spot before he was allowed to go.
Another friend was driving his moms mustang on the way back from a car show and was pulled over for the plate being obstructed. It was a clear piece that was part of the back tail/brake light cover. He did not get a ticket but was told remove of car will be towed. He had to physical break the clear section off to the LEO approval and was allowed to drive on.
Shocking that both were in Illinois.
Might just be up to the LEO discretion but might not be worth the gamble.