I believe you but I find it hard to believe LOL. Why would comprehensive pay for mechanical defects? Insurance is there to make you whole after a covered loss. Unless a tree fell on it or it got damaged due to a hurricane etc I just don't see how insurance would step in. Comprehensive covers any covered loss other than collision such as hitting an animal, flood, fire, theft, vandalism. And then you have to pay your deductible and potentially have your insurance policy increase because you now have a claim on it. Not sure if it's worth it but also not sure everyone is so lucky to have insurance cover a fallen out back window as a claim.