According to this BMJ article, in many countries that have a presumed organ donation policy, the family can override person's decision related to donating his/her organs:
(..) although Spain is often said to have a presumed consent system, in practice, the requirement to make sure people haven’t (at some point) expressed a desire to opt-out means that the deceased’s family is always asked for consent, and if they refuse then this is always respected.
In fact, almost all countries with presumed consent systems adopt a similar (sometimes called ‘soft opt-out’) system whereby family members are always approached to confirm that the deceased would not object to their organs being donated. This creates the opportunity for ‘family overrule,’ even where an individual has expressly signed up to be an organ donor. Rarely do countries adopt a system where the family has no right to overrule the presumed or declared wishes of a donor (Austria is one such exception).
Double checking with the family makes sense when purely using presumed consent. But I do not understand the rationale behind allowing them to overrule an explicitly declared wish.
Question: What is the reason for organ donation "soft opt-out" even if the person has explicitly allowed organ donation?