Students cheat because we have academic systems that reward those who cheat without getting caught. Instead of asking how we can catch people, maybe we should be asking why students cheat in the first place. I mean these aren't just unmotivated high school dropouts -- they're honor students, college students, etc. By the articles own admission, 80% of high achieving students admit to cheating. Hell, I went to MIT and cheating was even rampant there.
Why aren't students motivated to learn? Why is it that even good students don't feel short-changed when they cheat for the answers instead of learning the material? When you try to answer questions like that, you'll think less about catching cheaters, and more about reforming our ineffective, outdated, traditionalist educational systems.