Bob, it's naive to think that everyone will do as well as your relative with morphine, though that's also the thought of young idiot MDs who haven't seen many painful deaths. Liver cancer is almost always a gruesome, painful death, as with your liver shot, you can't handle the morphine. Likewise anyone with any sort of liver disorder (common in MS). Many people can become utterly deranged on high levels of opiates, having terrifying halucinations yet still in pain. Anyone with brain inflamation/infection will be in pain, as opiates increase spinal fluid pressure and thus increase the head pain. (I'm in that group, and the MS-liver problems group.) In some places, Hospice can use extreme measures and up the morphine until unconsciousness followed by death, but in others, this is not allowed or the staff is too afraid of repercussions.
I am a fan of Hospice, they helped my Dad's ALS exit along though he was begging to go days before, but think that their toolset should be expanded way beyond Morphine, and that anyone should have the right to say "enough" at any time and be assisted with any and all means. At present in the US, they are only allowed to opiate you to death, and sometimes that's a long, drawn out horror show.