This is only partly true. If an individual does not have an advance directive naming a health decisions agent or proxy, several states expressly designate default "surrogates," typically family members in order of kinship, to make some or all health care decisions. Only a few of these statutes authorize a "close friend" to make decisions, and then normally only when family members are unavailable.
Even without such statutes, most doctors and health facilities
routinely rely on family involvement in decision-making, as long as
there are close family members available and there is no
disagreement. However, problems can arise because family members
may not know what the patient would want in a given situation, or
they may disagree about the best course of action.
Disagreement can easily undermine family consent. A hospital
physician or specialist who does not know you well may become the
default decision-maker.
In these situations, patients risk having decisions made contrary to their wishes or by persons whom they would not choose. Moreover, family members and persons close to patients experience needless agony in being forced to make life and death decisions without the patient's clear guidance. It is far better to make one's wishes known and to appoint a proxy ahead of time through an Advance Directive.