Auto insurance companies in Oregon can now reduce the amount the insurance company will pay for in an accident that invloves a driver not listed on your policy. Yes, if the person driving your car lives with you, or doesn't but has regular use of your car, and they have an accident the insurance company can pay only the state minimum amounts of benefits. That's a maximum of $25,000 per person to a maximum of $50,000 per accident (shared). It doesn't take much to spend $25,000 - just a trip in an ambulance to an emergency room with some blood work and an MRI exceeds that.
This will happen if the person driving is suspended, expired, revoked, is intoxicated (alcohol, illegal drugs, prescription drugs), the vehicle is being used for business, or if it is used while committing a felony.
And always remember - if you excluded your family member or room mate on the application that means they are never covered, even in an emergency. Please think about exclusions before you sign them.