Wasn't much picked up on my comment here...........
In Jersey, I drive a 70,000 pound, 43' truck with air brakes for a career, with a basic passenger car license with no endorsements.
Taking this thought and adding to mine and you can see a bit of a pattern.
I echo Dave10's comment that it is good to have the knowledge. I think that is the whole point of the process. I have seen so many rigs driving recklessly and have been to my share of rv accidents while working which were caused by drivers driving like they were in their cars.
I am a fire fighter, and because of that in New Jersey, I am exempt from having to deal with any commrcial license requirements even though I am a certified operator of our 67,000+ and 74,000+ 3 axle, air brake equipped, top heavy aerial trucks.
Education, or lack of it especially when it comes to air brakes and big trucks can "wreck" havoc.
Rough estimate is about 1/3 of the fire fighter fatalities each year (30-40) involve motor vehicle accidents, and almost all of those involve rollovers.
Speaking of wrecking havoc.........
Take a look at this video of an incident in Indiana a couple days ago. Mind the language if you have sensitive ears nearby, the language is about what you would expect witnessing this type of incident. Minor injuries.
http://www.youtube.com/watch?v=yi8EzvjeeCk