As a semi-related phenomenon, I also feel like mathematicians are culturally prone to under-citation. I don't just mean that nobody cites older mathematicians like, say, Leibniz or Euler, for techniques they invented. But pretty frequently I'd read papers that really seemed like they were heavily indebted to a paper that came only a few years before but didn't appear in the 5-10 citations. Maybe there it wasn't mandatory to cite those papers, but it made it hard to chain backwards into the literature to get more context on methods and ideas. And sometimes it came off as the author trying to make a tool appear ex nihilo. I'm sure this happens in other fields too.