Do you mean for review, or even when they've accepted and ask for a camera-ready version? I always assumed all publishers need the source so they can do the sm

Do you mean for review, or even when they've accepted and ask for a camera-ready version? I always assumed all publishers need the source so they can do the small tweaks they do. [OTOH, I've seen claims many publishers already have a process for publishing Word submissions — something involving monks spending their lives typesetting everything from scratch? — and so when they do get a nice LaTeX, they throw the source out re-use the above process! Perhaps that was only about the bibliography though.] I've seen some Springer (LNCS) submissions, and those definitely included the .tex source. arXiv requires the source, mainly so they can re-compile them in the future with better tools [https://arxiv.org/help/faq/whytex https://arxiv.org/help/faq/whytex]. Unusually, they make sources available for anyone to download.