Here is the thing....
1. You don't know what you don't know... if you have been here for a long time, and this is the best you know.... Then sorry to say, you don't know what you don't know! Other airlines have training, techniques, open discussions, feedback loops that integrate and improve. Other places do this better... FACT.
2. The original gripe had very little to do with the quality of the trainers, but more about the system that they operate under. I would be sure that you can go to the manager of training and ask him or here what should change. Then ask him / her to circle on the list the things that they can change. The top of the crop is operating with their hands tied. We all know where the problems are to be found. Unfortunately it will take something major to change it.
3. If someone tells you they feel like they cannot engage in training due to the fear that the place operates under.... Then that is real. Take it as feedback (which may would agree with) and try to see a way forward to improve. Feedback is not something to be argues with. If the customer is telling you they have a crappy experience with what is on show, then that's the feedback.
My opinion only... The good trainers are worlds best. The worst are worlds worst... You would not believe how average some of the training is. Some is wrong, some is just absent, some is negative training, some is intimidating.... Some is by people who just don't care, and some is by people who just don't know any better.