There is one other aspect my DSis (mother of a severely autistic child now a non-verbal adult with the mental age of below 6 needing 1:1 supervision) came accross:
Parents of non special needs kids do not dare / feel uncomfortable sharing their "normal" lives (trouble at school, sleeping problems, teenage problems etc.) with her, fearing the reaction of: "I'd be glad to have your problems." (and - as she told me - often receiving this reaction, too. Not from her, she has non special needs kids as well.)