Primary rule of insurance is insurable interest. A roommate doesn't have insurable interest so they actually shouldn't be on the same policy unless they regularly drive the car.

Your point is kind of the opposite of mine. People can't buy a policy on something they don't own or have financial interest in.

Utah is the most complicated on the topic. Most Utah policies require that you list or exclude every resident of a household 14 years or older. Utah requires that the owner of the policy and the excluded driver sign the exclusion form. They only allow exclusion if the person is not licensed or has their own insurance.