Lesschumras: Fifty years ago most of the Rebbiam survived the war and couldn’t understand American kids. Many students acted frum just to graduate high school. Once they got into college they were free and drifted away from Judaism.
Now a days teachers take more of an interest in their students and can spot student that are starting to go off the derech. The teachers try to get them back on track before they go off the derech. Even the Hasidic schools have these type of programs this reduces the percentage that actually go off the derech.