Until the unrealized dawn of self-driving cars and autonomous vehicles becomes a reality, there will be negligent drivers and irresponsible people behind the wheel of motor vehicles. Even when self-driving cars become the norm, there will be technical problems and emergencies that could lead to a car accident. There is no version of the future where car accidents are completely eliminated. Mistakes will happen. So the most important thing we can do, as a society, is be prepared for these mistakes and take action when necessary.
Car accidents can deal terrible injuries to the people involved. Head, neck and spinal injuries could ruin a person. A brain injury could forever change their life. Broken bones and permanent scars could also drastically affect a person's future or career. These aren't hypothetical situations -- there are countless examples of people suffering like this due to car accidents.