Clear language is not just as easy for neurotypicals.

I'm not claiming that it is, as a general rule. I'm just claiming that the intrepretative assumptions they make about their speech are much more likely to match their audience's, thus mitigating the effect of unclear speech.

Your failing to know this isn't an autistic spectrum thing.

I didn't fail to know it; when teachers have said what komponisto complains about, I've understood what they really meant. But I also recognize it's because I made some assumptions about the teacher's disposition that someone wouldn't necessarily realize had to be made, especially if they were autistic-spectrum.

As a recent example, one time I was asked, "Did you come prepared to make a payment today?" Since I didn't know I would have to make a payment at that time, I said no, on the grounds that my failing to expect it is a lack of preparation. Then I realized they meant "Are you capable of paying today?" and were just using a roundabout way of saying it.