I've lost plenty of jobs because of it, and for the longest time I just figured people like to be mean, because when I was fired, nobody would ever say why, even when I pressed them for a reason. When I was shunned or excluded, people feigned ignorance and looked for a quick way out of the conversation when I asked why. It's incredibly frustrating and saddening feeling like people pick on you for no reason, when you know that there IS a reason, but nobody will say what it is, or how to fix it.
I've tried being extra friendly (people think you've got an angle), being strictly professional (people think you don't care about anything), more helpful (people think you're brown nosing), more talkative (people think you're a buffoon), less talkative (you become the guy nobody knows, and are the first to go at layoffs). And since there's no apparent rhyme or reason to their reactions, your life becomes a series of ticking time bombs until a relationship ends, a friendship ends, a job ends... Who you are means nothing if it slowly creeps people out.
I had one wake-up call when I was called wierd by my training buddy, him question why I even took part in the classes we were taking. I asked him why, he responded that my T-shirt was cryptic.
After explaining the print to him (it was a film reference), he thought everything was fine again.
That's sadly the level some people operate on.
Yup, people with severe autism get diagnosed early in their life, as child. They're clearly impaired by their autism, and get help.
People with a mild version get un(der)-diagnosed, especially women. They're expected to just blend in with society yet when they have difficulty in life, they're being told to e.g. "man up". Which might work with NTs shrug.
If you don't see a disability, its not there, right?!
Yeah, that's the one billion dollar question indeed, one even specialists are unable to answer. (Both me and my significant other asked our specialists this very question.)
Autism is a (developmental) disorder. In our society you're expected to behave in a certain way, and if you don't you get burned. You get called a witch, a hermit, an oddball, a nerd, or what have you. People with mild ASD can function in our society, but there will be situations where they have to adapt to society's norms instead of their own.
If the world worked the way I'd envision, a lot of small talk simply wouldn't exist. Simple example: I get fucking annoyed by this terrible, inhumane and fake way Americans seem to greet each other with how are you which they don't mean one iota of. I cannot stand it, but I have to endure it, and the American culture is coming for you. It slowly creeps up into the world, for good or bad (not saying its all bad!). Another example: looking someone in the eye when you talk to them. I don't want to! I get over-sensitised! I prefer to stare to something beautiful peaceful, such as clouds, nature, or some one point on the wall which has a slightly different colour.
The good news is that people with mild ASD, with adequate help and understanding from their peers, can have a functional, successful life and many have bend the positive side of their ASD to something fruitful. Whether that's some scientific advancement, great invention, financial success, or a plain happiness is less relevant than it might seem.
If you don't understand how to interact with people, you don't understand. You need help to figure it out, or you need help to realize you don't need help.
And that does wonders for you when trying to be diagnosed and, if you are lucky, treated.
BTW, I also don't think of ADHD and ASDs as diseases either. Like you said, it's more like the way we are wired. I am wired in a somewhat odd way, but I wouldn't trade my brain in for the standard model, even if it is inconvenient sometimes.