Thankfully, not all schools:

Some educators have rejected [Turnitin] and other anti-cheating technologies on the grounds that they presume students are guilty, undermining the trust that instructors seek with students.

Washington & Lee University, for example, concluded several years ago that Turnitin was inconsistent with the school’s honor code, “which starts from a basis of trusting our students,” said Dawn Watkins, vice president for student affairs. “Services like Turnitin.com give the implication that we are anticipating our students will cheat.”

Trip Gabriel, “To Stop Cheats, Colleges Learn Their Trickery, July 5, 2010″