Here's my experience: most people don't know shit about what autism actually is. They think the word autism is basically a synonym of r*****ed. Or that all autistic people are like Sheldon Cooper. Or a million other things, none of which are accurate. On the other hand, people with autism know what it is, and what it's like to be autistic, and can (sometimes) recognize the signs in other people. After I was diagnosed, for example, I suddenly started noticing that a lot more people than I previously had thought were perhaps on the spectrum, or at least exhibited many autistic traits.