I bet if someone done the research on number of accidents per capita of RV owners verses semi drivers with CDLs I bet the numbers would sway in favor of the RV owners having less accidents. Probably less deadly accidents also.
Accident statistics don't favor semi 18 wheeler drivers. Their contention is that they are on the road daily so the exposure to having an accident is higher. They also refer to poor car drivers putting them in accident situations (cutting the truck off, stopping distances, changing lanes without notice, etc). Yet, semi drivers also are the CDL drivers with the 'enhanced' license.
For the most part RV drivers tend to be 'more occasional' drivers of the RV, are typically not in as big as a hurry to get somewhere, and often are more careful driving the RV than their car.
It would be interesting to compare the accident stats in states without any need for an enhanced license to tow over 10,0000 pounds (or whatever that magic number really is) or drive a diesel pusher that weighs more than 26,000 pounds against the same accident data in states that do require the enhanced licenses and see if the enhanced license changes the statistics. I suspect there is no statistical difference between that data.
With modern tow vehicles with far better suspension, brakes and power than twenty years ago towing a trailer that weighs 9950 pounds or 10,050 pounds there is probably no difference in performance. The 10,000 pounds is just a number, not really a safety marker with modern tow vehicles.