The $24 raises the insurance amounts, is primary, has no deductible, covers medical bills and damage or theft of personal property...
Maybe I didn't need that extra layer but it is giving me peace of mind. The regular is secondary to one's own insurance and since I don't even know if my regular car insurance covers us in this situation, that may be a moot point.
The way insurance companies drop people anymore for any little thing I also didn't want to take the chance.
Speaking of Costco I am bummed that they are severing ties with Amex as all the other major Amex seem to have fees...