In 1930, the UK Government introduced a law that required every person who used a vehicle on the road to have at least third-party personal injury insurance. Today, this law is defined by the Road Traffic Act 1988, (generally referred to as the RTA 1988 as amended) which was last modified in 1991. The Act requires that motorists either be insured, or have made a specified deposit (£500,000 in 1991) and keeps the sum deposited with the Accountant General of the Supreme Court, against liability for injuries to others (including passengers) and for damage to other persons' property, resulting from use of a vehicle on a public road or in other public places.
Auto insurance is financial protection, and not just for the investment you made when you bought your car. After a really serious accident, bills for damage and injuries can easily reach into hundreds of thousands of dollars. If you happen to cause such a wreck, the victims could sue you. In the worst case scenario, assets such as your savings and home could be seized.