We all talked about this at length yesterday/last night. I originally felt the way you do, but had my mind changed by some of the posters on here. LE likely (IMO) knows the license plate number and owner/driver of the vehicle already, but by releasing this image, they encourage this person to come forward of their own volition. If they dragged them in, or approached them first, this person may be on the defensive, may lawyer up, may flee out of fear of being a suspect. By releasing the photo and stressing that this person is not a suspect or POI, this person may feel comfortable talking to LEO.