I'd say this stuff happens way more than anyone realizes.
I went to a private Christian school and one male teacher was fired while I was there for fucking a 16 year old girl because, frankly, she was hot and she relentlessly pursued him. After the story came out, she tried to play the victim to save face with her parents. The teacher was charged with statutory rape and, apparently, not much came of it because he didn't do any jail time and he is now a cop.
I later found out that 2 of the football coaches and a baseball coach were all fired for the same thing... fucking horny high school chicks. In all of the cases, the girls pursued the men.
I suspect that in most cases of a male teacher with a female, the girl does the chasing and in the cases of female teacher with a male student, it's the same thing. We poor dudes just can't catch a break. I'm sure there are a few predatory shitbag men out there who deliberately try to fuck their students but I'd say they're few and far between.