I could be misinterpreting your comment, but it reads like a broad misunderstanding of the role, economics, and value-add of contemporary publishing.
Here is a (now somewhat old) breakdown of per-article costs, contrasting open access and subscription journals: https://www.nature.com/news/open-access-the-true-cost-of-sci...
From my perspective the main values that an modern open access publication provide are primarily emotional labor: 1) herding cats: all those reviewers and editors that are volunteering are incredibly flaky and need to be hounded by phone, in person, etc. This can't be automated because everybody ignores bots. 2) resolving disputes. hopefully the median paper goes through the process smoothly, but any dispute involving prominent researchers will require dozens of hours of careful mediation, fact-checking, and follow-up. 3) generally being a responsible institution (not suffering fraud or embezzlement, planning for change over time, etc), which is valuable because humans don't have the time or capacity to judge every piece of content from scratch and fall back on reputation. All of these tasks require competent, savy, and highly trained folks, or the whole thing falls apart. Many in the old (subscription) world would say that open access publishers have already cut corners at $3k/article, and if you read around on the internet everybody complains about how long it takes to get responses or resolve disputes, so maybe they are right.
If these numbers sound totally bogus to you, maybe you should jump in to the publishing business and undercut everybody with superior service? Try writing a business model. As to whether we need publishing at all, i'd also try convincing researchers and authors to just post their results on blogs or wikis, which have zero barriers, require no new development, etc. I think authors/researchers value the services publishers provide, even apart from the whole branding/reputation/incentives game. Even pre-print repositories involve a degree of labor to review, moderate, and resolve disputes.
"automatically typeset using LaTeX" is only a norm in a few fields, which are all relatively well resourced and tech-savy. The fact that extra typesetting labor is involved in fields that don't use LaTeX might be one reason that pre-prints have been slower to take of in fields not covered by, eg, arxiv.org.
Another class of costly labor is copy editing and getting details right. This means things like tracking down every single citation and making sure they exist and are formatted correctly, spelling corrections, making graphs color-blind accessible, etc. This is hard to automate with current tooling; a lot of time and resources are currently being spent on next-generation open source publishing/manuscript pipelines to make this sort of thing more machine-verifiable, but it's going to be a long struggle to get authors (legitimately busy and distracted and over please-do-everything-this-new-disruptive-way-please-ed) to change their established field-specific workflows.