you know what has a 0% hallucination rate about the contents of a text? the text
What text are you reading that has a 0% error rate? Google search results? Reddit posts? You seem to be comfortable with the idea that arxiv preprints can have an error rate that isn't 0% so 'the text' isn't guaranteed to have no errors.
Even assuming perfect text, your error rate in summarization isn't 0% either. Do you not misread passages or misremember facts and have to search again or find that you need to edit a rough draft before you finish it? We deal with errors all of the time and they're manageable as long as they're low. The question isn't 'can we make a process that has a 0% error rate, that's an impossible standard' the question is if we can make a system that has an error rate that's close to or lower than a person's.
The reason why is because these systems scale in a way that you do not. Even if you have savant level reading, recall and summarization such that you would make Kim Peek envious, how many books worth of material can you read and summarize in 10 seconds? 1? 5?
Could you read and summarize 75 novels (10 million tokens) with a 0% error rate? I'd imagine not and you certainly couldn't do it in 30 seconds. In fact, this would be an impossible task for you no matter how high of an error rate that we allowed. You simply cannot ingest data fast enough to even make a guess at what a summary would look like. Or, to be more accurate to the actual use case, could you read 75 novels and provide a page reference to all of the passages written in iambic pentameter? I can read the passages myself, I just need for you to find them and tell me the page. You'd probably take longer than 10 seconds and you would almost assuredly miss some.
Meanwhile an LLM could produce a summary, with citations generated and tracked by non-AI systems, with an error rate comparable to a human (assuming the human was given a few months to work on the problem) in seconds.