My biggest issue with the horse industry is pushing young, green horses too hard and too fast. The 7 year old Morab I ride was being ridden as a 4 year old by a girl who wasn't paying attention and the horse was already unsure and cautious about the jump. He was being walked back and forth over the crossrail. The worst happened and she kept asking him to go over it when he wasn't ready, he stepped onto the plastic pole (Which should not have been used!) and it snapped underneath his belly, scaring the living daylights out of him.
He was put in the pasture for months until I started working with him. I had to start everything from scratch. He was so frightened and he has such a terribly good memory, he would not even touch a ground pole. Needless to say it's been 2.5 years now and he's made such progress.
We're jumping 2-2'6 consistently and I've jumped him 3' to see if he could do it. He still has issues with crossrails and new jumps though, it still takes him looking at the jump before he will jump it.
And all of this because he was pushed way too far out of his comfort zone way too fast. I'm not saying he should never have been made to go over the jump, but all in the hurry of trying to make him a lesson horse, he was pushed too hard, an accident happened and here we are, almost 3 years later and he's still scared.