Say that I am towing my friend's new travel trailer with my pickup and hit a low hanging tree limb and destroy the trailer's electric awning. Whose insurance pays, minus the deductible, of course. ...
When you are the vehicle operator, the financial liability for your mistakes is your liability. Whether or not your insurance pays depends on the terms of your policy. Quite likely you will be out of pocket. Even if your liability insurance covers it (unusual), paying out of pocket and not making a claim might be the less expensive option long term, because your insurer can escalate premiums even if they don't pay a claim.