I just realized something: Wayfarer's variable cost would mean that if you gain it with Populate, and you have a Livery in play, the only way you can get a Horse from the Wayfarer gain is if you choose to gain it first, and if there's any previously-gained cards that turn, the last one was $4 or more. The reason for this is that the Horse is gained immediately after the card that caused it to be gained. So, if Wayfarer is not the first card gained from Populate, the last-gained card would be either a Horse from the previous Populate gain, or a card less than $4 gained by Populate. Either way, the last-gained card is guaranteed to be no more than $3 if Wayfarer is not the first card you gain. So aside from the obvious case of top-decking, that's another situation where the order would be relevant