[jacquesgt]

That actually is how car insurance works. There's a property insurance component ("collision" and "comprehensive") that insures you against loss or damage to your property. Then there's a more expensive liability insurance component that insures you against liability as a driver of any car. The property insurance portion is optional as long as you own your car outright.

[Nrsolis]

Correct.

Liability is the "required" part of insurance in most states. It follows you from car to car.

What has likely happened is that they person who rented the car didn't have insurance of their own. That seems likely, since it's kind of pointless to have automotive liability insurance if you don't own a car. Even more so if you're used to purchasing insurance at the point of sale when you rent a car.

[dkrich]

Incorrect.

Car insurance generally "follows the car." If you lend your car to your buddy and he gets into an accident, your insurer is the primary. If you don't have insurance on the car, then if he has insurance it may cover some of the associated costs. That all gets settled in court.

Collision is not required, but liability is.

[ricardobeat]

Driver liability is primary. The owner's insurance only comes into play in case the driver isn't insured or it doesn't cover full costs. That's the standard at least.

[dkrich]

You insure a vehicle. If the vehicle is insured, then that insurer is the primary, so in the event of a claim, that is the insurance company on the hook.

Now it is true that when you sign an insurance policy, part of the contract makes the insurance company liable for the driver if he is in an accident in another vehicle and for whatever reason there isn't a primary or the primary uses subrogation to recoup damages from that insurer.

But that is not the most common case, and certainly shouldn't be used as the standard for what to expect would happen in this case.

Have you ever heard that women's insurance rates are typically more expensive than men's because they lend their cars more often to others? Now why would that be if the drivers were responsible as opposed to the vehicle insurer? Again, civil law is not black and white. Insurance companies have teams of lawyers in every major city in the country to fight their way out of claims when possible and certainly there are times that they succeed in recouping some damages from other insurers. My point was that this is not the norm. The primary insurance company is the first in line when a claim is to be made.

[ricardobeat]

That's true for covering the material damage, but in my understanding the liability for corporal damage/medical costs is not as black & white, and falls on the driver first.