As of today, Iowa's "move over, slow down" law expand to include all vehicles with flashing lights. This video from one of the Iowa DOT's I-235 cameras shows how quickly things can go wrong when a driver doesn't move over.
As the DOT says in this tweet, "amazingly, no was seriously injured." You'll see the crash in the upper right corner of the video.
At about 8 seconds into the traffic camera video, you see a white car drift to the right, moving much too close to a vehicle stopped on the side of the interstate.
At 12 seconds, the white car runs into the parked car. The white car flips into the air and lands on its top on the interstate.