Photos preserve scenes, evidence and injuries which change over time. Photos often show things better than you can describe them. Photos sometimes reveal details you do not notice at first with the naked eye. Photos are dramatic. They highlight whatever they are focused on, without the distractions of surrounding sights and sounds.
Photos are difficult to contradict.
An insurance company may say you are wrong when you describe how an accident happened or how badly you were injured, but it is much more difficult for it to deny what is in a photograph. Photos help you focus your claim. You select which photos to show to an insurance company. Photos impress insurance companies. They show that you have been organized and thoughtful in preparing your claim.