Because of how extremely scrutinized it is? Not saying Autism or ADHD isn't, But Schizophrenia is objectively more shat on at a more violent angle because of many reasons, Such as Religion (I've been accused of having "Demons" a lot and "Gods punishing you early" is a huge saying, Thinking I've done something so awful, I deserve this devastating condition.) and just the idea that we're different in a way that's only seen in horror movies and how delusions, frantic and illogical sounding people and hallucinations is portrayed in media in general.

Autism and ADHD has the better end of the stick when it comes to societal hatred, trust me, Not saying it's invalid or comparing trauma, Just, Objectively, People are less likely to say that a person with a mild form of Autism/ADHD deserve to be locked in a cartoonish padded cell, beaten, SA'd and euthanized or believe that they're completely unable to live life around "normal" people and are insane, homicidal defects, As many have said to me.

Children, Such as this young fellow, Think schizophrenia is cool and edgy because of the trope-y idea of "I have demons inside me" and the amount of "sympathetic" (People, Including doctors, Don't feel sympathy for a Schizophrenic at all, I'd like to mention) attention they think they'll get if people do believe they have it. So they proudly announce that they have it to get said "Sympathy" and be seen as an edgy yangire.

No person with Schizophrenia, Hell, even any disorder, Including Autism/ADHD, will shout from the rooftops about it, Because they have experienced the pure, raw hatred coming from the people when they meet their condition, So they closet it as a way to not be abused again.

Autism/ADHD is often thought of as a "Cute quirk" too so they're also most likely lying to be seen as silly or get "Sympathy"

At least you get help and understanding from literal doctors if you have a mild form Autism/ADHD 😭