I understand, but people also have very different standards of communication clarity. There are a lot of hidden assumptions, even when you're trying to be 100% clear. Sometimes people can't put their thoughts into words, or they don't have the capacity for what you think is clarity. And in this case it's just a very minor mistake. The person might not be native, or they may have been failed by their education system, or they might just be tired or stressed. There are lots of valid reasons why communication can degrade. I'm a bit autistic and struggle with ambiguous meaning or communication that doesn't fit patterns I'm used to, sometimes to a truly irrational degree, and I'd like for others to speak my language more so I can understand them better, and I'd like to be able to speak their language more, to make them understand me better, but it's just sort of the way of life. People are very fluid beings, not at all tied to rigid logic. People are also all very different, and their efforts all come in different forms. They emphasize different things, focus on different things, not just communication efficiency. What I've learned too with other autistic people is that everyone's standards for communication clarity are different. I don't think you can speak a universal language that everybody understands perfectly 100% of the time. What does happen is that people who talk to each other often learn each other's language, able to talk more concisely and efficiently, but you can't really expect that of strangers on the internet. Of course "birds of a feather flock together" as they say. People in the same internet communities might have the same interests, consume the same media, have the same discussions with the same people. But there's no getting around communication degrading. In the worst case you just have to ask someone what they mean, maybe clearly explain your issue with the ambiguities, and wait for disambiguation. Learning to ask precise questions so as to elicit the best response from someone, to immediately get the answer you seek, is also a lifelong challenge. It's not worth getting upset about a single instance of degraded communication, if you can even call it that. I'd be more upset with the universe for making us all so very different.

This seems like such a strange take. You make it sound like it's cost you effort to translate the error, but how are you quantifying that effort? If effort efficiency is something you're striving for, it doesn't feel like it makes sense to correct the mistake (which costs effort to do)

The gap between the two - what they said and what they meant - seems so small it probably took more "work" to correct them.

I'd go as far as to say that the work to correct them will never be repaid by the saved effort of not having to encounter this particular mistakes from this particular person ever again.