Why do cons keep arguing that the education system is indoctrinating students?

Because it is....it REGULARLY teaches LIBERAL OPINION as fact when it is not. You're proof that indoctrination exists as your posting a LIBERAL web site stating their OPINION as a FACT...please LEARN the difference between book learning and intelligence...while libs in academia may have the first they lack the later....the wise sage once said ....those that can .....do....those that can not ...teach