A heartening number of students and teachers will even tell you the equation states that energy is equal to mass times the speed of light squared. What people know about Einstein's equation, like much of the useful and practical science they know, is not part of the curriculum and was not learned in school. In fact, though this is by far the most recognized equation in history, it is not recognized as an equation at all. Another way is to ask them to use it. Accepting this contradiction is not their fault.
Much science is taught by memorization.
Still, it is a shame students don't have a chance to use the equation. It is elegant. It is powerful. It lets them answer exotic questions. Scientific notation is implicitly part of the standards and is used in examples given, as is the metric system.