@pleonasm - The thing is, it's not really simple at all when it comes to people, because there are so many more choices in treatment. Often someone who wants to choose euthanasia is choosing this over a continued existence that is made possible by advanced medicine.
Or you might have a patient who has some form of dementia and doesn't really have the ability to choose whether or not to end their lives.
So who gets to choose? Should it be family? Doctors? The government? It's not a simple thing at all. And that's all got to fit in as well as possible with euthanasia ethics, which are far from clear.