Liability insurance is purchased by someone to protect them in the event they cause a harm. The person who owns the vehicle purchases the insurance, and that protects them against anyone that they harm. If they let somebody drive their vehicle, that person is also covered, so any harm that they caused while they’re driving the vehicle is also included, too. You, if you’re walking, you’re running, your’re bicycling, you’re in another car, and you’re injured by this person, you’re covered and you’re the one who gets the insurance money to compensate you for injuries that they caused you.