"spouses, no need to add them to the contract as they're automatically an authorized driver as per the terms of the rental agreement."
That's advice for N America. In other countries, you do need to go to the desk and have the names added - generality for free. In the UK for example, if the spouse name isn't shown on the rental contact and you were stopped by the police, you could be deemed to be driving the vehicle without authorisation (and therefore without insurance) and could be arrested.