If we represented truly the worst-case scenario, then copyright infringement can’t be a really big problem, because we don’t have that much

I think the lesson here is that fair use practice in education has to lead legislation, not be driven by it. MIT has led the OER movement. As a pioneer and as a sponsor of “openism” it has probably tread further than many lesser institutions have dared; thereby defining the space within which use can be considered “fair” ahead of those who are more risk averse.