A magical spell doesn't actually ask about your willingness. The information is always gathered directly from the mind by magical means. As the information is extracted directly from your subconscious when you are conscious, why wouldn't it also extract it directly from your subconscious when you are unconscious?
Moreover, both Resurrection and True Resurrection have the caveat that:
If the creature’s soul is free and willing, the creature is restored to life with all its hit points.
It is up to the DM to determine if being able to query the soul is an extra power that other spells do not have, or if the spell's text is simply pointing out the obvious limit of only being able to ask souls.
In either case, if a creature that is dead can -- at some level -- decide if they are willing or unwilling and magic spells always takes the answer directly from the mind anyways, I don't see why a spell wouldn't be able to get the information from an unconscious creature.
The spell doesn't doesn't give an option of "if unable to determine willingness treat it as unwilling".
Spells only do what they say they do. Does it say that it doesn't affect unconscious creatures, or that unconscious creatures automatically get a saving throw, or they automatically pass the saving throw, or automatically fail it, or does it specify how to interact with the unconscious in any way? No. Does it say that it can determine willingness? Yes.
Therefore the spell can determine the willingness of an unconscious creature.