Yes. By law, all drivers and passengers in the car must wear seat belts on every trip, whether long or short. The driver will be held responsible if their passengers are not wearing their seat belts. Seat belts are built to be worn by only one person at a time. Fastening a seat belt around two people or doubling up may be not only unssafe but illegal as well.
Drivers including passengers aged 16 or older caught not wearing a seat belt by the police may be penalised for not wearing the suitable seat belt or restraint when a rental vehicle is moving. It is also the driver's legal responsibility to make sure a child inside a car is properly restrained in an appropriate approved child restraint, even for short trips.
It is an offence to drive while not wearing your seat belt or to allow passengers to travel in a vehicle when a seat belt is available. Disobeying a lawful order is a serious offence and maybe liable for a substantial fine as well as demerit points. Learn more about seat belt road rules and penalties by clicking here.