It's about canon law, not theology. The Catholic bishops have to be in sync with the Magisterium as Catholic institutions (primary, secondary, colleges, universities, hospitals, etc.) have to be in good standing with their bishops to retain canonical status. No Catholic institution wants to lose that status, least of all the current religious founders, sponsors -- Jesuits, Franciscans, Oblates, Dominicans, Holy Cross Fathers, Benedictines, etc. -- of these institutions. In regard to the church's teaching on birth control, each Catholic institution has to mirror the same canonical face regarding church teaching, which will be different from the positions of the employees and public in general. Evangelical officers, Mormon, Jewish, etc., likewise have to abide by their official beliefs. Administrators of these religious institutions don't want to overleap these religious teachings, only to be disqualified as legitimately Catholic, Evangelical, Jewish, etc. Not easy for administrators.