Because it's summer and pets can get overheated in the sunshine, they often (cats and dogs) seek the shelter of the shade if they are outside. Oftentimes they will lie under a car or other vehicle, usually right behind the tires. I know two families who sadly lost their beloved pets by running over them. Imagine their pain (both owner and pet). The pet is usually asleep when the driver backs up over them so there was no time for the pet to escape danger. I know this is a sad subject but if by its mention it can help to save an animal's life by making us more aware of looking beneath our vehicles at all times before we proceed, then it's worth mentioning.
Of course, we know that small children should never be left unattended so that they won't be in danger of moving vehicles. I have heard the heart wrenching stories about children being run over by their own loved ones. I'm sorry to put this image in your mind. But, we must also be aware that even when the little ones are accounted for and well supervised by ourselves, there are other children in other home situations, perhaps not being monitored appropriately. Additionally, older children whom we feel are mature enough to watch out for themselves when it comes to moving vehicles in a parking lot or driveway may act spontaneously to chase a basketball flying in the wrong direction or may be running or darting (during a chase or game) in the direction of the moving vehicle without thinking. There are many reasons that even a mature older child may not think quickly enough to preserve his or her own safety or the safety of one's friend or sibling.
Please watch out and be aware of what's going on at all times when operating your vehicle especially when backing up when you may not have perfect visibility.