Used too funeral homes either put a clip on flag on the vehicles window gutter or a magnetic one on the roof or food of the car. With todays car designs & plastics etc I guess a mirror placard is the only universal place left. Yes head lights were supposed to be on. You followed the Limo & hearse and did not stop for signals etc. People had some common sense. So did cops.
Really I can’t remember the last time I saw a funeral procession. Most families in my region have started opting for holding the funeral service immediately following receiving friends. Friends and family then the next day meet at the grave site for a short graveside service. That means no procession from church or funeral home to grave site. Really it’s a good idea. Evening service allows more persons the opportunity to attend and IMO less stress placed on the family the next day.