There is a trainer I know with methods I would consider abusive at times. The majority of the time I see her ride she is not getting after the horses, though they have a very concerned manner of going when she is on their backs. Then, if the horse misbehaves, all heck breaks loose. Lots of yelling, lots of whipping because they did not respond exactly as she saw fit. I don't have a problem at all with people getting after horses when necessary, and I understand that some folks may have firmer methods than I. I still consider her methods of "discipline" to be abusive.
However, she's a VERY well recognized and respected trainer in her area. Ladies who wouldn't lay a hand on their "precious baby" as it ran them over like a bulldozer will stand in awe as she smacks the crud out of their "precious baby". I spent lots of time there growing up, and I was able to recognize that there wasn't something right about this when I was an early teenager. Some worship the ground on which she walks. No way would I ever have a horse in training with her. There were two arenas (covered and non), as well as a pasture to ride in, so I generally tried to avoid riding in the same arena as her. I tend to try and avoid riding in the arena with someone anyway, but if she was having one of her "blow ups" then she would completely disregard any other riders in the arena in favor of disciplining the horse. Personally, I didn't really feel like having to get out of the way to avoid getting run over because someone's horse was being somewhat finicky that day.
What would happen if I had tried to do something about it? First, I would have had to find a new boarding barn. The options around here are slim to none as far as decent barns go especially for the level of care the horses receive, and I likely wouldn't have been able to continue with my trainer. For a period of time I would have been out of a job. Assuming I had called animal control and they thought the concern was worth investigating they would have showed up to find a barn full of well fed and watered, well cared for horses with all of their needs met. Had she been riding a horse at that given moment chances were that it would be behaving perfectly well and the ride would be uneventful.
What could I do? Either struggle to find another barn that my trainer would travel to so that I could continue my training with my horse. I could call some sort of authority, nothing would come of it, and if she found out who called then I would be in the same position. The best I could do at the time was to keep her off of my horse and avoid riding in the arena with her. So that's what I did.
It's not always cut and dry.