Again, if really a teacher wanted sex and really was willing to coerce the student to get it, all the student has to do, these days, is speak.

What if it remains private? Yes, that would be the problem, but why would it remain private? There is not just no incentive for it to remain private but all the incentives to speak in cases of coercion.

I'm not at all sure that all cases of students making accusations are believed or result in trouble for the teacher. If they reach your attention via the media, then surely they have. I think very few girls would want to expose themselves to that kind publicity at all, and I don't think they are guaranteed of vindication.

But to the extent you are right, we could argue it is the system operating well. Since the student can speak up, the teacher is deterred from making unwanted advances. The idea that an unscrupulous student can ruin a teacher's career is a big problem, one way or the other, and we would do well to turn down the hysteria and use some perspective.