The difficulty is, as the Warshauer article indicates, that, given the actual extent of plagiarism, it's not really possible to enforce the policies. The freshman comp chair and my faculty advisers had me on the carpet many times over variations on the following: "John, you have to understand that there are departments like Cinema or Victim Studies that are trying to get the university to recognize that their introductory courses can qualify for the freshman comp requirement. If a student can take Cinema 101 and get credit for freshman comp, we lose enrollment. That means your job." (It also would mean the jobs of the professors who teach the graduate assistants, of course, who were the ones who were hectoring me.)
So if English 101, freshman comp, gets the reputation of flunking too many students for plagiarism, there will be that much more incentive to establish or take substitute courses where the policing may not be as effective. But beyond that, any university has got a scandal if any percentage of students -- take whatever statistic you find on the web, or whatever you think is right, ten percent, 30 percent, 60 percent -- gets sent up on formal discipline. Think about it. Don't go to Faber College -- there's a 30 percent chance they'll flunk you out for plagiarism. I don't know what they'd do with that in the US News ranking.