I can only speak for the UK, but here, there are two types of power of attorney: the health one designates someone to make decisions about medical treatment if the subject is unable to; the finance one allows the attorney to manage the assets of the subject when needed.
The key point is that the whole process should be far easier if these things are setup in advance, while the person is still able to make their wishes clear, i.e. while they can still say who they trust to make decisions for them.
The key point is that the whole process should be far easier if these things are setup in advance, while the person is still able to make their wishes clear, i.e. while they can still say who they trust to make decisions for them.