One of the reasons I like a tow bar on the back of my car. If someone rear ends me they will get noticeably damaged. Unfortunately on my current car it is an electric foldaway unit so cannot be seen.
I once got rear ended whilst driving a Bedford CF camper, the OP reversed and drove off down the road laughing. They hadn't noticed the rear step on the CF had gone straight through their radiator and that no damage was done to the CF.