It's not the education system that has a left wing bias... it's reality
Honestly I think reality is centrist. That is, there is no grand theory that works for all social organisation. It just happens that the mainstream right is working against the data that we have at the moment. I think if "we" started moving left, we could eventually move far enough left that the data would be against those trying to take it further left. I think it's better to side with the data than to claim allegiance to any particular side. Unfortunately siding with the data necessarily entails changing your mind on things from time to time, and this is seen as politically weak.