I think if Nendou ever sees Kuriko he would immediately recognise her as his best friend Saiki, I think he wouldn't even notice there was anything different about her
Like when you meet all of the parents the characters make so much sense (I mean really, the backstories for all of the characters very clearly show how they were shaped. The world building in Saiki k is seriously top tier, it's almost too good for what it is)
oopsy long post
Kusuo is all disillusioned because his father sees him only as convenient and his brother sees him only as a rival +his mom is either completely blind to it or just doesn't care/doesn't see a problem with it. (But despite being pretty mean he's subconsciously pretty selfless, also because of his mom.)
Kusuke was seen as convenient the same way Kusuo was by his father and they both probably tied their respective self-worths to that but unlike Kusuo he was seen as the apparently less useful one- and instead of just being a little toxic, since Kusuke's a genius it was blown out of proportion into death machines and other generally very drastic measures. (A lot of people have pointed out Kuniharu and Kurumi actually, just another to say these things)
Kaido turned to a fantasy world because of an overly strict mother, whatever's up with his father might have something to do with it too.
Nendo's a very respectable himbo because his mother's amazing.
While Teruhashi's parents aren't shown I think their absence actually says a lot anyways. Her brother's super out of control for whatever reason and she goes insane if she's not validated for a single second, I can see this being because her parents weren't there to rely on.
yes, i think kusuo had it better than everyone around him.
unlike shun, both of his parents are around and neither of them are strict or disrespect his son's privacy.
unlike riki, both of his parents are alive.
unlike kokomi, he at least has parents that we know are around and care for him.
unlike makoto, he wasnt used for his powers and turned into a national sensation from (likely) a young age.
(no, kuniharu asking his son to teleport him to work is not traumatic or abusive. i would ask my kid too if they could do that.)
unlike reita, he doesn't need to go through horrors of being unsure who around him is alive or dead, thus isolating himself from the alive because "living people are bad"
and i swear to GOD if i see yall pull out the "b-but kuusuke was a bad brother 🥺🥺🥺" thing...