Well, to be fair, football injuries are almost entirely related to the contact sport of impact they are. Not to the training per se. I think comparing that to regular training is kinda apples to oranges. Now I have no statistics whatsoever, as to how many line men are injured lifting heavy. (I am sure there are a few)
I think the bottom line is the extremity of how far one pushes the activity. If a coach is seeing a trainee losing so much form or pushing a said trainee and the trainee has more of a die hard mentality, then I would think the coach may step in, but not sure they "all" do really!?!? At that point, the risks are going to be elevated higher than a trainee who stops well under his limits.
I have seen trainers in gyms push clients however, as I always thought that was a component of the job ie" motivation and some drill sarge stuff.
That all said, doing safer exercises such as seated presses against a back support, etc. etc. etc. are going to have less impact, than an explosive exercise like C&J's/snatches that has quite a bit of technique involved in getting things right, to be really safe.
I have no horse in the race, but again, the more you push an extreme, the higher the risk/payoff. If they feel it is worth it, so be it. I have no problems. I feel extremely heavy compound lifting is worth it for me, but would I say they are safe or even safer under the tutelage of a coach, maybe, but not near as safe as staying well within your means.