> 1. The allistic (non-autistic) person is not hearing what I'm saying.
It's possible that they're not smart enough, literally. I find ease of communication is uncorrelated with whether they're on the spectrum or otherwise. It's their raw intelligence level. Somehow the bandwidth between our brains is really high. They often know what I'm saying before I've finished my sentence, because they've already figured it out and have predicted what I'm going to say. But if you're talking to someone with 110-120 IQ, you really have to slow down and spell things out for them, and some things they will actually just never grok unless you have 30 minutes to explain the abstract foundational concepts behind what you're saying.