What is assisted? A car fitted with the self-driving computer, but rather than driving the car it instead compares your actions with one the computer would normally do. What is this comparison for? To determine whether you are a safe driver -- a Safe Driver Rating (SDR).
Self-driving cars will become the new gold standard for determining who is a safe driver -- and failing to meet that standard will result in higher insurance rates.
What does this have to do with malicious hackers? They can fudge the self-driving computer to silently and gradually increase your insurance rates by misreporting your SDR.
What about cars that are neither fully autonomous nor "assisted"? Simple: they don't get built/sold anymore due to being unsafe.