... and if you do not know that an opt-out is required to not have your organs removed, then how can it be said that you have willingly contributed them. And if your organs are removed by default, without you actually willing that this be the case, then how can this practice be called "donation"?

So instead, shall we call it "organ retrieval", "organ harvesting" and so on? All rather ugly words. But when the words that accurately describe what you are doing appear ugly, instead of looking for words which inaccurately describe what you are doing, perhaps you should ask yourself if you should be doing what you are doing.