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.
