From what I can understand, you are asking why it is easy to put fingerprint marks on a new car versus a car that had been detailed, correct? If so, some reasoning behind this could be that the wax takes the beating from the fingers and does not show the damage, but the new paint on the car takes the damage as there is no wax to protect it. If you are talking about new paint from a repainting job after an accident, then it is different. Resprayed paint NOT from the factory will remain soft for 30 days as it out gases. This does not occur with cars from the factory as the paint is heated to high temperatures that out gases the paint.