one of my friend earlier used to say the similar thing. We hardly reach at the speed of above 40 kmph then why to buckle up. I gave him a actual demo. Saw in my mirror that no one is benind & applied sudden brakes at speed of just 30 kmph & his head banged... He got to now that even at low speed the impact can happen. Then onwards he has started wearing the seat belts even he wants to move out his car from parking.