Wow, is there a clause like this in the US?
That is stupid, if I bring anything in in Europe and it is damaged by them they are responsible not me!!!!
It has nothing to do with laws or otherwise. However, most companies will include a release of liability in those long arduous contracts you don't read and just 'agree' to!
As the other poster said, it may not hold up in court, it may not comply with regulations and laws. However, the cost of suing Apple over something like that is well beyond the cost of repairing the cosmetic damage, even if you win. The if is a big if, we all know what Apples legal team is capable of.
I think this is just going to have to be chalked down as a 'lesson learned' situation for you in the future. Whenever I take anything in for repair, I always ask the repair person to make a notation of the condition of the item before I release it to them. So, rather than my word, it's theirs. I make THEM document any previous blemishes or wear and tear. Then, if I pick it up and there is a ding that wasn't there previously, THEY are the ones who said it wasn't there in the first place! Voila! It's not my word against them, it's them against them. I keep a record of what they noted as well. Some of them like it, because it protects them too, they get to write down that there's a scuff mark here or a shiny worn spot there.. so I can't come back and say they did it!
However, there's simply no reason not to ask. Just be polite, give them a call or go up there, and explain that you received the item, got it home, and found damage. In the future, have the person you release it to note any existing wear, and inspect the device in reference to any indicated wear before accepting it after the repairs are completed.