The difference is that the tube driver (assuming there even is one) can't just decide to take a slight turn from the planned route, while the car driver really might.
It does happen, it happened to me — a driver was distracted (because they were texting while driving) and they veered from the traffic flow and I was hit at 40 mph. The EMS worker who responded to the scene told me two things: 1. They almost never pull people alive from this kind of accident, 2. This kind of head-on, no brakes, distracted driver accident was happening more and more. This was 10 years ago.
