Years ago, when I was a teenager and had a summer job, I worked at the local officer’s club. I was supposed to help the regular employees, and that included going along with them to pick supplies up.
When we had loaded the supplies up, and we were seated, I was wondering why the guy wasn’t driving off. He just looked at me and said “Buckle up” and nothing else. As soon as I buckled up, he left, and that was the end of it. He didn’t explain anything, he didn’t lecture me. I guess it was his rules.
There’s no rational reason, but it stuck. I’ve never driven on public roads without a seatbelt. Our work compound is very much like an army base, and I sometimes drive unbuckled on the premises. I’ve got no excuse, but we’re only allowed to go 15mph maximum. Needless to say, not everybody obeys the speed limit
My brother’s wife is very well educated. She’s an MD, and has a school-age son. Yet she has a nasty habit of driving unbuckled. When I’m driving, and she’s in the car, she also tries to get away with it. If I see that she’s unbuckled, I say “We’re not going anywhere until you’re buckled up. You should know better.” She just laughs, and lifts her butt up, and buckles in. She has a strange habit of actually sitting on the seat belt. Doesn’t seem very comfortable