UK government changes website guidelines due to buggy screen readers

I'm afraid not. AFAIK, screen readers don't apply any special processing for DFN tags. Speaking as someone who's using a screen reader to read this thread and proofread this comment, I'm not sure I'd want them to either, and I hadn't even heard of them until today.

Also, screen readers are able to speak through several, possibly hundreds, of different speech engines, so you would have to teach each of those engines to deal with these corner cases separately. Given that many of them were developed ten plus years ago and are now no longer under active development despite continued widespread usage, that's not really a realistic goal.

N.B. AFAIK is spoken by my screen reader/speech engine combo as "uh-fake". As a blind software developer, I have much bigger problems to worry about than memorising how my software speaks abbreviations. I of course don't speak for everyone though and clearer communication is always an excellent goal.

You seem to be assuming that a screen reader's job is to somehow communicate meaning. It isn't. It's my job to listen and decide what I'm hearing. If you read "ect.", your brain automatically corrects it to "etc." because you're used to seeing it often. It's probably subconscious, right? It works exactly the same for me. I'm well-versed in the spelling/grammatical/other errors many people make when writing, the only difference is that I consume them via my ears, not my eyes.

Or, to put it another way, think about a guide dog. Its job is to actually guide a blind person, make decisions, keep them safe. It actually has to think. I prefer my assistive technology as dumb as possible though, so I use a cane. Its my job to use the cane, take in what it's telling me about the ground and area immediately around me, and quickly make decisions based on that information. The screen reader is more like a cane than a guide dog, basically.

Not at all. Seeing errors like "ect", use of the wrong words like the all-too-common mix-up of "then" and "than", and even the omission of dots in things like "eg" and "ie" is very jarring to me. It usually pulls me out of automatic reading in order to consciously work out what the author actually meant. Even when I've worked it out, I find it hard to substitute the real meaning for what's literally there. Not that I necessarily blame the author, as I understand that mistakes do happen, but it does noticably harm readability for me.

I do find your description of your preference on assistive technology very interesting, as it differs from the preferences expressed by my visually impaired friends. They get varyingly amused and annoyed by their screen readers not understanding idiomatic things and reading them too literally. I wonder if the difference is that you're the kind of technical person that reads Hacker News, whereas they're both arty types who don't really do computers any more than the average person does. I suspect that were I to ever need to use a screen reader, I'd prefer the dumb ones like you do.