The people who do not wear their helmets for short rides also probably do not fasten their seat belts for short trips. Where is it written nothing tragic can happen close to home?
I do remember many years of cycling without a helmet before anyone ever thought about wearing one. I even suffered a couple of potentially very serious spills that could easily have resulted in brain injury. My first helmet came with some cautionary information about how debillitating and expensive a brain injury can be.
I like wearing a helmet. I know I am better protected and safer. I also have my mirror mounted to the visor on my helmet and would be lost without it.