I'm just following your logic...or lack thereof. It is not my position.
It is your position, as I understand it, that direct observation is required and that secondary effects are meaningless. Ergo, finding a fingerprint at a crime scene doesn't mean anything in this view. By your statements, it is not an indication that a person was there. Only that a fingerprint exists. This follows directly from your wake/boat example.
So it is not me, but you, that is making this claim. Unless you want to rethink your position concerning observations.
I said we can match the found fingerprint to a person.
What happens when the fingerprint database does to match it to a person?