90% of the time, a human will either 1) not notice the debris at all, and plow into it 2) brake to a sudden stop, causing a massive hazard for all around or 3) swerve dangerously into another lane.

Just this morning I watched a car come within inches of plowing into a gigantic orange traffic barrel. He was going 30MPH on a quiet residential road but he simply was not paying attention, and braked just barely in time to stop before hitting it. And this is not some unusual thing, this is how people drive. I've nearly been run down in a crosswalk at a four-way stop sign by drivers who simply decided that they did not need to look forward while going through the intersection. And you think that humans are going to have a good record at spotting and handling small debris when cruising at 70MPH? Good luck with that.

One thing I will say about humans: when they're about to run over you at low speeds, you can usually get them to stop by shouting at them. I doubt computers can manage that yet.