I'm afraid that I have difficulty with the concept of requiring special education and licencing for every change in conditions. This one is for towing trailers. I do not know the statistics, but I rather doubt that accidents involving trailers (where the fact there was a trailer had anything to do with it) are a rather small fraction of total accidents. Partly simply because most incompetent trailer drivers just don't do much of it. And most trailer drivers do do an adequate job, as shown by the fact that these accidents are rare.
If you are going to require special licencing for towing, why not for many of the other circumstances where the conditions differ from the car and conditions you learnt in? Some rather higher than trailers on the list might include rural driving for city dwellers or city driving for rural dwellers, driving in remote areas, driving without ABS, driving with ABS, and of course, the old faithful one of a four wheel drive licence!
There are a number of reasons why none of these are ever likely to happen, including the limits they would place on youth employment, and the backlash from voters like myself - who has been towing trailers for over fifty years - and the only accident I have ever had involving a trailer was when an idiot (phone user I think) ran into the back of my trailer while I was stationary, waiting to turn right, and had been for some time.
And if education and licencing does not prevent new drivers from having accidents while drunk and way over the speed limit, when both zero alcohol and speed limits have been a major part of the education, why do you think it would work for trailers?

