Here's one example showing why people might be reluctant to speak out about wasteful training: (Sorry, this is a bit long!)
Early in my PhD, I was made vice-president (or something like that; I don't actually remember) of the university's Society of Fire Protection Engineers (SFPE). This title was really only a formality as there were no duties aside from some training that the university required. The organization existed mainly to get external speakers every once in a while. The organization was purely professional. Keep this in mind.
The most annoying training could accurately be described as "frat boy training" in the sense that it seemed to be targeted specifically at heavy-drinking fraternity members. The training lasted about 2 hours as I recall and had to be retaken yearly. It involved groups of roughly 100 people watching videos and participating in discussions about (basically) why you should call for medical help if someone passes out after drinking too much. (There were some other lessons, like telling us to call a certain phone number to report on people who seem to be "suspicious" but are not breaking the law.) The entire event seemed to be motivated by lawyers' desire to reduce the university's liability in the event that someone drinks too much and dies.
The first year I was in a leadership position in the local SFPE group I attended the training and thought it was a huge waste of time. None of the training applied to our group. We never had any social events, much less ones with alcohol. Plus, I don't need to be told to call for help if someone is obviously in medical trouble.
Given that, in the the second year of the training I arrived early and politely asked the presenter about why my group was required to attend this training. The presenter responded rudely along the lines of "Of course you have to take the training. Sit down and do it." Not only that, apparently they had a panic button, because soon after that two security folks came in to escort me out of the room for being belligerent. (I don't recall the presenter doing anything that seemed to indicate they were calling for security.) I was really struck by this because I was polite the entire time and was actually going to take the training again.
After being removed from the room, some admin came down to chastise me. I carefully explained to the admin that I don't believe this training is relevant to my group at all, particularly as one of the only graduate students in attendance. The admin continued to chastise me, and told me that I would have to reschedule my training for another time even though I had not missed much as I recall.
Later the same admin contacted me to tell me that yes, in fact, my group was misclassified, and we will never have to take that training again.