I think it’s less that “media literacy is not taught” but that media literacy is not learned. Like @audiomodder said, everyone is graduated regardless. So, on one hand, there are students who either will not or cannot learn the material (for one reason or another, such as disability, stress, family, etc.) and teachers who get a laundry list of things to teach and not enough time or support to teach it.

Ultimately, the problem is a lack of focus on education as a society. Children are pulled in too many directions, and teachers aren’t given the resources needed, so we end up with a broken educational system.