I have nothing to base this on, but I suspect kids do better because they lack experience, so there is nothing to resurface. Their lack of memories prevents any sort of introspective reevaluation of their life.
I think this is a little uncharitable to kids. Do you not remember the stressors and ruminating thoughts of childhood? To say nothing of children who have experienced trauma. Perhaps this could apply to pre-object-permanence infants, but by the time they're undergoing surgery (hopefully...) they've had years of conscious experience.
Hopefully I'm not being too uncharitable, your idea is certainly plausible. I'm also just musing which feels disrespectful to the terribly interesting expert take in the ancestor comment, but I cringe whenever I hear arguments that I can reduce down to "being a child is not at all like what it is to be me", as it's been used for centuries to suppress their behavior and excuse abuses
