The fact they do not charge you an additional fee for prep on a vehicle they are selling has nothing to do with the fact that a prep probably costs them several hundred dollars in material and labor, most of which is lost if the rig is not delivered. Things like cleaning, washing and waxing etc, are no benefit in a couple of days when a few more customers walk through the rig or it rains or a flock of seagulls converge. If they had to remove protective coverings the dealership now has an unprotected rig. All of that costs money, and they either need to get it from you, since you created that cost, or they have to get it from the next customer. Which do you think is more fair?