Thanks for the input everyone. I guess I'm guilty of worry-warting, prompted by the fear-mongering from travel books and government websites, perpetuating the bad-road myths in name of C.Y.A.
Texan, the "roads" you're referring to that offer "shuttles" ... what are they? Do you mean privately owned roads like the one inside Denali NP that's only open to the tour bus concessionaire?
Just my personal opinion, but taking a shuttle is something I wouldn't do, same thing with cruise ships and airplanes. If I'm not in control of the conveyance, I'm not interested.