> When I vote to close on StackOverflow only one other vote is required to close.

I think it's a per-tag reputation threshold.  Closing a question tagged `foo` requires a high reputation related to `foo`.

Outside of E.S. almost any Emacs questions are tagged `emacs`, and so any user who has answered a lot of questions about Emacs can tend to close other Emacs questions.

Here on E.S. the tags are spread much thinner, for obvious reasons.  You being rather active in making corrections when people have used tags inappropriately is probably working against you for this particular purpose :)