True, all the operators you mentioned have pilots with a wealth of mountain experience, but how many of them have had training other than that which is required by the CPL syllabus? The training they've received is through experience.
To that point, a friend Jeff Cooper, once commented that there are three things all men think they are expert in, by virtue of being born male, two of which are shooting and driving. For helicopter pilots, I would add a fourth, and that is mountain flying. I routinely ask pilots about their mountain flying experience and knowledge, and always hear they understand mountain flying based on, for example, their military experience, the FAA syllabus, and having flown some in the mountains. Prior to taking the Canadian Helicopters full mountain course, I had taken a number of fixed wing mountain courses, flown extensively in the mountains of the west and Alaska, and considered myself somewhat experienced in mountain flying. After being exposed to the mountain course in Penticton at Canadian Helicopters, I was absolutely blown away by what they teach and how much further developed it is than anything else I had been exposed to. I guess that isn't surprising when you realize they have been developing this program over about fifty years and essentially all they do in Penticton is teach mountain flying.