that is becouse we at the higher end of the spectrum are not as obviously autistic, recrouters just notice there is "something" about us that doesn't feel right, and they dont trust that.
for lower functioning autistics, it's clear. "he's autistic, but that doesn't matter for this job, so i hire him".
now i'm not saying that jobs for higher autistics are negatively effected by our traits (they aren't and often being high on the spectrum can be an advantage), but recrouters dont realise what we are.
also, they dont usually know there even *is* a higher end of the spectrum, so disclosing makes them think of us as unfit lower-end autistics, which are unsuited for the job. (generally, exeptions exist).
this isn't fair, not by a long shot, but that's just the way it is.