Possible case : me. I often forget my seat belt. Fortunately, most people remind me about it and then I immediately fasten it.

The reason is simple. I think I use a car, always as a passenger, like 3 times a year. When I used to drive, it was such an automatic gesture I’d never forget it. But it’s so easy to forget when it becomes very rare. Everything is hypnotizing when you enter a car. I’m glad the driver reminds me, but I could be OP’s lost one.