Some people are good drivers in all types of vehicles. The definition of good is certainly open to interpretation. Many make the transition to large vehicles and are comfortable going down the road. Others not so much.
Personally I have driven large vehicles most of my life and am relaxed while doing so. I have had a CDL for as long as they were required and even maintain it in retirement. The people who seem to need some training would be those who we all see from time to time driving all sizes of vehicles, hunched up on the wheel with a death grip on it looking for all the world like they are scared half to death. Obviously that doesn't encompass every driver on the highway or every RV driver.
The underlying problem becomes who needs additional training and will it be any improvement over the current status quo? I am not a believer in the adage that says if you have the desire and funds to purchase a large vehicle you are instantly qualified to hit the highway in it. Too often those who might benefit from some training/education are those who don't think they need it and/or are unwilling to seek it out or pay for it.
Opinions will vary all over the place on this issue and there doesn't seem to be a universal solution. Personally I have never seen any training that was completely useless or a waste of time. Some is simply more beneficial than others.
Press on, I'm going camping.
