I wrote a paper this year (after about a 15 year hiatus) and apparently submitted papers, this was to an elsevier journal, now automatically go though a plagiarism detector of some kind that gives a score that can't exceed some value. We actually failed the first time because we'd published the paper on Arxiv first, which seems like a big flaw in the system. I don't have a lot of faith in, nor do I support automated detection like that, but it does happen systematically now.