For instance, I've given family my old laptops, and they setup their accounts after they take ownership of the device. The way I interpret your comment with regards to my scenario is that Apple should disregard the fact it is locked to their iCloud account and unlock it for me, because I can prove I was the original purchaser - even if they accidentally left it at my home or I steal it from their home.
Is that what you meant, that if I can give Apple a receipt then I am the de facto owner no matter what? Or am I just way off base?