I think among all your examples, the Santa Claus story is unique in our society in that adults tell it to children with a completely straight face and actual intent to deceive.

Apparently so; but not the intent to maliciously deceive — to deceive in order to weaken and exploit, in the manner of a con-artist or quack.

My point was that the intended epistemic status of statements made in everyday life, especially around children, is not all that clear. It requires analysis — indeed, literary analysis — to figure out what is a truth claim, what is a fictional canon, what is a parable or metaphor, and what is just pure pretend.

People cry over fictional deaths — children and adults, too. That involves some sort of participation, suspension of disbelief, or perhaps entering into the story (eitsing, a possible antonym of Hofstadter's "jootsing" or jumping out of the system). This is not unusual or pathological in the slightest. It is a normal part of human culture.

Being able to drop into a role, participate in play-acting or ritual, and so on — that's a social skill.

And they get angry at adults who tell children the truth about it. Or children who tell younger children the truth. Or sometimes even children who admit knowledge of the truth.

Maybe this is the point on which the apparent disagreement here turns. I'm aware of the story that parents do this, but I've never actually seen it — neither in my own (Christian, American) upbringing, nor others I've seen.

Mind you, I have seen parents be upset when someone mocked their child for thinking Santa was real, or made the child disappointed or anxious with the revelation. But that's a bit of a different thing; the upset seems explicable by the child's unhappiness.

But the idea "many or most (Christian, American) parents actually become upset when their kid finds out that Santa is a story" seems to me to itself be part of the story.