I thought so as well, untill I drove 70 miles between Ashland and Duluth a few years ago and counted 38 deer carcasses on the side of the road. Keep in mind that Wisconsin is not Idaho. At that time the deer population in Wisconsin was in excess of one million, which is an incredible population density for a wild animal. So the study was probably true for Wisconsin, but it wouldn't be for out west. And if it sounded like I thought it was then I worded it poorly. I just found their results interesting. Plus road traffic in Wisconsin is quite a bit more than in Idaho and Montana.
Found this article on line. Definitely supports that wolves are the problem in Idaho. By the way, good luck with your wolf hunt.
http://www.examiner.com/article/dealing-with-declining-elk-herds-idaho