Just explain what will happen if the authority caught you violating the rules , kids nowadays are normal being stubborn but still they are concern about us parents so eventually they will use to that, and tell them about the fines to pay if you are being held .
I agree the best way is to explain well to our children what happens if they don't wear a seatbelt. In addition to being fined for violating traffic rules,
not using a seatbelt can be dangerous in the event of an accident. Usually 10 year olds are still easy for us to advise, I believe if we communicate well,
our children can understand this. And don't repeat it again in the future, because sometimes children need an excuse if we as parents forbid something.