[Django Unchained] Why didn’t Django and Schulz just say “we want to buy Django’s wife”

Not science fiction but I’ve seen every fictional universe here lol. Why didn’t Schulz just be honest and say “hey listen Django has recently been freed and he wants his wife back, we will pay you whatever you want”? Why did they feel the need to have this elaborate lie of “me and this black slaver would like to buy your best fighter”?