...and it turns out the "empty" cardboard box is half filled with metal pipes, which your human eye had no way of knowing in the split-second before your car collides into it in 65 mph. Your car screeches, loses control, and swerves into the neighboring lane.
But luckily a following self-driving car already detected the presence of an obstacle using radar. It detects your car maintaining speed. Within several milliseconds it evaluates chance of collision as VERY HIGH, starts evasive maneuver, scratching your car at a speed which is still uncomfortably high but not likely to cause a fatal accident.
Several weeks later a team of automobile experts review everything recorded in the accident, improve the algorithm to reduce the chance of accident even further in Edge Case 783645: the preceding human-driving car plowing into a small road obstacle at 65 mph. Firmwares are automatically upgraded during the following months.