I think the liability enters in when the customer is never informed that the machine is storing copies, and then later the information shows up in a damaging fashion.
In that case, I think a Jury would be empathetic to a customer who says "he never told me it was storing those documents".
Let's pretend I sell cell phones. I sell you a phone, and you use it for 2 years. At the end of your contract, you turn the phone back in to me.
I didn't mention to you that the phone records every conversation you make, and then I sell that phone to someone else and they can listen to everything you've said.
From the uninformed customer perspective, you had no reason to suspect it was recording you all this time, and I imagine you'd be pretty upset with me not telling you.