It's difficult enough for driverless cars to know where the lines on the road are. I don't think we can expect in the near future to be able to not only detect pedestrians, but to have an idea what series of events may happen during an avoidance maneuver. There's a lot of things to go wrong.
However, stopping distance in real-world scenarios is wayyyy farther than in practice runs, because even a second faster braking by the driver can save a hundred feet. So robotic braking (that we have today in passenger cars) could improve the distance a lot. But...
Trucks are still 10-20x heavier than passenger cars, and there are practical upper bounds to the size of their brakes and the g's they can pull. If a passenger car normally stops in 388 feet at 65mph (not uncommon) and it would stop at 196 feet at 45mph, a truck at 45mph would stop in 265 feet. So yes, the truck could in theory stop faster than the passenger car.
But passenger cars don't just slam on their brakes in front of trucks (often). They also just drift right the heck into the truck. Perhaps mechanisms could be developed to safely merge away, and they'll probably be developed in passenger cars first. But there's no denying that a dedicated roadway would not only save repair costs for passenger-vehicle-only roads, it would remove the risk of colliding with passenger vehicles no matter whose fault it was.