I feel like Waze has killed the high beams flashing warning, although I miss it. It sounds crazy as a say it out loud, but the signals between drivers always gave me warm feelings of some kind of community with other drivers. Now everyone on the road seems much more internally absorbed or focused. Cars are quieter, podcasts instead of radio, etc. While they were never very common, CB radios were also less rare in cars (we always had one for road trips and both my grandparents had one in on all the time in their cars).