The vast majority of people would like to avoid such scenarios for themselves and for their loved ones. There are some remedies, but none of them are fool-proof. The problem generally arises when heroic measures have been applied in an emergency situation, placing the patient on life-support systems. Once those systems are in place, it is sometimes very difficult to remove them.
THE FAMILY. When this choice is delegated to the family to make the decision of whether or not to terminate life support, it leaves them in a situation that is very difficult. They have the understandable grief that comes with a critical illness. For them it is like choosing between life and death, even though they are assured that the patient cannot recover, and for all practical purposes, is dead. It is especially hard if the patient has not expressed his/her point of view about such a situation in the past. The advance of technology has made it extremely important that everyone consider this question and make clear their preference.
THE PROFESSION. Dealing with death and suffering on a daily basis does not make it easy for medical people to make decisions about removing life support. They make an effort to be as dispassionate as possible about such situations so that families can make informed decisions. Added to the moral, ethical, and humane considerations, they also must keep the legal risks in mind. No group is more subject to the risks of litigation than the medical profession and institutions. The medical professional does not want to be accused of pressuring the family for the removal of life support, or to be second-guessed by other medical personnel in a court of law.
The result is that the profession tends to err on the conservative side. That means they tend to resist family efforts to terminate life support unless clear evidence exists that this was the wish of the patient when he/she was in good health. Probably the worst cases are those where the patient has no problems with breathing or heart function, but must be fed through tubes. Thus, the alternative becomes feeding or starving the patient. Even though the patient may be brain-dead, such a decision is very difficult to make.