What if the patient opting for euthanasia is a tetraplegic (therefore, a person that lost their ability to press buttons) whose condition emerged from an underlying disease/condition that has no cure for the foreseeable future and that’s why they chose euthanasia instead of suffering? How such person is even supposed to “press the button”? In this hypothetical example, I’m considering that such person is capable of explicit consent through speech before several witnesses and some judge or their lawful representative, saying something like “I, John Doe, as an exertion of my human right imbued free will, I hereby authorize my euthanasia because such-and-such and whatsoever… being done by M.D. Luke Doe as an anesthesiologist professional authorized by me to do so”.
I mean, the very purpose of the right of euthanasia is to consider this right especially for people who’re painfully suffering from irreversible conditions, such as terminal diseases, conditions that bring such unbearable suffering for those who have them, although I’m more inclined to the thought that “Life should be a right to everyone, but shouldn’t be an obligation nor a duty to anyone” independent of any underlying conditions. In any case (be it euthanasia only for terminal diseases or euthanasia for anyone who wants it), of course explicit consent is a must, be it verbal or handwritten, and I think that the long bureaucracy is enough for the patient to authorize any assisted euthanasia.
It’s actually not nice, not for local wildlife, for example. Biomes exist for a reason and if anything changes abruptly, evolution can’t keep up with these changes, resulting in extinction of several species. Just like flowers are blooming in Antarctica, a rainy and green Sahara is as beautiful as a rose with thorns under its petals: really beautiful, but ominously dangerous.