You joke but this was a real concern back then. Lots of deaths and serious injuries from getting thrown around in the car in otherwise survivable lower speed impacts.

My parents were rather particular about me wearing a seatbelt, even though that wasn't necessarily the norm at the time. Of course 3yo me wasn't too happy about it but that changed after my dad hit the brakes once and I hit the backrest of the front seat. I actually think he did it deliberately to teach me a lesson and it likely wasn't half as bad as I remember it but that was a time when cars didn't necessarily have seatbelts and people came up with the most ludicrous excuses not to wear them if they did.