Non-owner insurance covers the liability incurred in at-fault accidents. Liability protection pays for the medical bills and property damage of those you have hit. The minimum non-owner policy will meet the state minimum insurance requirements, keeping you compliant with the law.
A non-owner policy does not cover the rental car or the borrowed car itself; rather, it provides finances for the other party’s injuries and damages only. To get the car itself repaired, you will need collision coverage, which is part of a full coverage policy. Because you are not the owner of the car, a non-owner policy will not provide coverage for it. The insurance company assumes that the car owner has their desired coverage for their vehicle since they are responsible for registering it.