Because some people are attempting to teach it in schools. Try to teach astrology in schools, and see what happens.
Oh the horror.
Try to teach astrology in schools, and see what happens.
Astrology and all sorts of New Age nonsense is taught in schools.
As far as the analogy of astonomy to astrology and evolution to ID, it doesn't really hold up. Not to say that there is any merit to creation science or ID, just to point out it is a flawed analogy and using it just makes the person using it seem to be intellectually dishonest or dumb.