Part of what might make this reasonable is that this process takes who is moving in together as a given. Say you and I want to be roommates, and you happen to know that I have a pathological fear of sleeping in big bedrooms. Clearly the efficient thing to happen if you're a normal person is for you to get the large room and me to get the small room. But how much do we pay?
It seems rather unfair of you to incorporate that information into the bidding system and bid up the price of the small room (a sort of strategic bidding). But it also seems unfair that if we both answer honestly the system has a good chance of making the smaller room priced the same (or more than) the big room.
With any other roommate, especially one who didn't know about my pathological fear, I could expect to pay less for the smaller room. These "external authorities" might reflect such widespread notions, as well as avoid the risk of strategic bidding that can occur after roommate selection is fixed.
It seems rather unfair of you to incorporate that information into the bidding system and bid up the price of the small room (a sort of strategic bidding). But it also seems unfair that if we both answer honestly the system has a good chance of making the smaller room priced the same (or more than) the big room.
With any other roommate, especially one who didn't know about my pathological fear, I could expect to pay less for the smaller room. These "external authorities" might reflect such widespread notions, as well as avoid the risk of strategic bidding that can occur after roommate selection is fixed.