While I agree with some of what you are saying, I would be willing to bet a pretty penny that most public education systems across the globe perform just as poorly in teaching about dissimilar cultures. As Rumsfeld already said, “We are taught to view the world through the eyes of our own culture.” However, that does not mean that we can simply blame public education for its inadequacies. As individuals part of a global community, we have the responsibility to teach ourselves about foreign cultures when others – or in this case public institutions – fail to do so. If we refuse to accept this responsibility, then we only serve to perpetuate a system of ignorance that leads to so many of the world’s problems.
Perhaps one reason for this problem is that until relatively recently, many people could not afford to travel outside the US, let alone cross the big ponds on either side of us. I would be willing to bet, even as a pessimist, that as the world continues down the path of globalization and international travel becomes more affordable, public education systems will begin to require their students to take courses covering different cultures. Although the light in which such education systems choose to cast different cultures will likely continue to be a problem.