TBH it doesn't really bother me if they don't wear a seatbelt if they want to increase their chances of being fatally injured I'm all for that. At least then they are dead and can no longer be a danger to other road users. But what does alarm me is that it is probably indicative of them not having insurance or a license, bald tyres or some other defect with their vehicle or even themselves.
In a 13 mile journey yesterday (by car) on quiet rural roads into St.Ives I saw 7 people using mobiles whilst they were driving and of those 4 did not have seatbelts on. The roads were pretty quiet as well. This afternoon I was cycling in town on the Brommie going shopping when in a residential street I saw a Peugeot 106 driving erratically toward me. It wasn't hanging around. As it got near I saw the driver was a nurse (feemail, blonde about 28-30yrs), yes a nurse, texting with her right hand while at the same time trying to hold the steering wheel with the same hand to steer the car, badly. She had her other hand in her handbag. As she drifted toward and past me I shouted Oi! Her window was down. For showing my concern and alarm she shouted Fkcu off! immediately back. I mean a nurse and in uniform. Shocking. Not a porter but a genuine SRN. The calibre of nursing staff has definitely deteriorated.