Does the foundation laid by 'Once there, he or she must alight from the vehicle and proceed to the mailbox, then return to the vehicle, turn it around and proceed to the road.' logically support 'They should never get out of the vehicle.'
Once there, he or she must alight from the vehicle and proceed to the mailbox, then return to the vehicle, turn it around and proceed to the road.###They should never get out of the vehicle.