Do you know why? In particular in the U.S. public schools, if anything that is taught outside evolution (like creationism), the professors' contracts(or tenure as they called them) will not be renewed. These creationist professors will not get promoted and worse, may lose their job. I read just few days ago, one of the top universities, sorry couldn't really reamember which one but was either Cambridge or Oxford, they are planning to introduce a degree in creation science.