You say we haven't gotten there as a society yet and I say we haven't gotten there as individuals. I really don't think most people, and I definitely include myself in this, know themselves and the world well enough to make such a tremendous decision by themselves in the abstract. It's one thing to want an euthanasia if you're in pain and want it to stop, it's an other to say "just let me die if something goes wrong" when that possibility is a remote and abstract thing.
Most of us have lived very sheltered lives. Most of us haven't felt what it's like to be really, really thirsty. Or really, really hungry. Or really, really cold. Or really, really tired. Or really, really lonely. Or really, really scared. Or all these things at the same time.
I can definitely imagine many people would sign a "don't help me if I'm in danger" waiver out of principle or motivated by some romantic fantasy. Then they end up shitting themselves in a freezing hole in Alaska because they ate bad berries, and they're crying and regretting everything and would be willing to do anything to be out of this place. Suddenly the lofty ideals and the romantic movies start feeling really dumb and absurd.
The principles don't matter anymore, the survival instinct kicked in a long time ago. Fortunately you have a satellite phone and you manage to call the rescue. "Sorry sir or madam, but you did sign a waiver. If you want help you'll have to pay the $300,000 standard search and rescue fee in advance. Thank you for choosing the Walt Disney Search and Rescue Services. Have a pleasant evening!".