I wonder why that is.
Another phenomenon unique to MO schools, is that you can be making out with your girlfriend and still be considered a prize student.
Here's a story I think is typical. At one MO high school I know about, the salutatorian, and ace Talmud student of the class, had a series of girlfriends, girlfriends he most definitely touched, occasionally in the hallways of the school. He flipped out in his senior year, went shomer negiah (with the last of those girl friends) and continued on to hesder yeshiva and top shiurim at YU, and later Ner Yisrael.
I think his story is typical of the other good students in this class, except he was smarter and had more girlfriends than average.
The last of his girl friends, incidentally, married a boy we'll call Charlie. Charlie went to an MO school in another state where he got fine grades, only he acted out in ways large and small. He was the one who brought the booze to senior trip, and so on.
Charlie flipped out in Israel, and now is on the faculty of a mainstream yeshiva.
Had either Charlie or the salutatorian attended a black-hat yeshiva their behavior would have labeled them "at risk." Both would have been expelled, blacklisted, destroyed. And, I assure you neither would have ended up lamdanim, and proud members of the Orthodox Jewish community which is what they both are today.