One accident might set back consumer driving for 50 years, but not commercial. The safety record simply needs to be much better than human drivers, which shouldn't be too hard, because one driver is already taken out of the equation. And there are billions upon billions to be saved, in our corporatocracy of the USA, it WILL happen. Bad roads shouldn't be too much of a problem, they can just use humans on the bad roads, the bulk of our highways are in good shape. Snow is an issue, yes, but remember that they will have the highways perfectly GPS mapped, great reaction time, and commercial vehicles can have big ugly shrouds to keep cameras clean. There is also the possibility of hiring temporary human drivers for the worst snow days, but I don't see that happening because I honestly think the robots can have a much better safety record in snow. The plastic bag/rock thing could be a problem, that could be partially solved by just assuming it's a rock, pulling over to the side and waiting for a remote human to identify it, and clearly mark the truck as autonomous so the humans on the road know to expect different behavior from it. That's not a perfect solution, but we have thousands of the smartest people working on it - there is enough money at stake, it will be solved.