Every red hot female teacher I fancied when 15 turned out to be a lesbian. Well they must have been, right, if they didn't come on to me? I mean, all the sexually developed teenage girls had no trouble getting old men's dicks. I'm sure you can see the subtle point I'm hammering with a sledgehammer folks.
But as to your second point CC, about the minor feeling lucky, not abused? It doesn't matter what the minor feels. Not, certainly, as far as the law is concerned. Yes, the lines that are drawn are arbitrary but it's a 30 year old idiot who doesn't adhere to them concerning his 15 year old female charge.
Of course there has to be compassion shown in grey area cases, like in the case with the teacher from Eastbourne. France has a law that discriminates crimes of passion doesn't it? Maybe the same could apply here. One teacher going off once with a minor is a crime on a completely different level to Savile for example.