She's just normal.
The main cast runs the gamut of just about every
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(anime LI character trope) on the spectrum - he may as well have used a dartboard with entries from that site when designing the characters. When it came time to set up the second floor, the only thing the game was missing was someone
without any significant abnormalities in personality, trauma, or life circumstances. Someone other than Maya who had the normal attitude towards the premise of the game.
There's a reason her parents are so explicitly involved in her life - in comparison to the next tier of normies below her, Otoha is
comically normal - Touka being extremely sheltered, Uta-chan who constantly brings up having to watch her grandpa slowly die, and Chika who's balancing the entire world on one finger after the loss of her mom. (And before you say Makoto - she's the most malevolent and self-centered human character in the game. Fight me.)
Otoha's actions are pretty consistent with someone of inconsistent maturity who doesn't know what she has until she loses it, and aren't abnormal enough IMO to label her as truly
"callous" - especially when Io hates everyone and says things like she actively hopes other people fail and Kirin is... well, Kirin. If anything, Otoha's the calm to Kirin's callous, since she's likely not realizing how she's taking the things you mention for granted.
Either way - while I think Touka has the most potential for radical character development of any main girl in the game, simply because of the sheltered normality, Otoha isn't too far behind. Everyone's going to get dragged through the shit in this game, and since they've seen the least of it, as you say, they're going to get the worst of it.