Most states have insurance laws that require drivers to have at least some automobile liability insurance. These laws were enacted to ensure that victims of automobile accidents receive compensation when their losses are caused by the actions of another individual who was negligent.
It is often the case that the cost of repairing the damages to an older car is greater than its value. In these cases, your insurer will usually just "total" the car and give you a check for the car's market value less the deductible. Many people with older cars decide not to purchase any physical damage coverage.