Not so, by my logic you can not be liable for paying VED on cars that no longer exists, but that does not imply that you can not pay VED or that any VED disc are invalid or that you will not be guilty of a SORN offence if you do not either pay VED or declare SORN on an undeleted registration.
Again, shopping bags are not a car for any purpose but SORN liability exists merely on the undeleted registration and not on the car.
Tony