If you drive with someone who tailgates, first send or TAKE them to the optometrist - bet you they need glasses or a new prescription.
I found that once I got my first pair I became much more aware that I'd developed a bad habit of creeping up on the car in front of me.
As for all of the husband-wife stories, I'm divorced, but my business partner incessently directs me whenever he asks me to drive him anywhere. Now mind you it's usually 3-4 blocks so he can pick up his car from the service bay, but I still have never convinced him that I actually HAVE made a left turn or seen a working traffic signal before!
He never corrects other people, that would be rude... but we've known each other for 3 decades and familiarity apparently does breed a sense that he has a duty to nag.
Bob is a good driver, but where does that "master of the known universe" attitude come from? Last time out I handed him the keys to my BIGASS Suburban and invited HIM to drive it.....
Vengence is mine, sayeth the Ford!