It's not so much that the updates are "driven by EU"... they're driven by the Russian mod creators, that doesn't really update their mods before they get the patch. And generally, every update, RU gets it first, and EU/NA afterwards. It's hard to release an update for 9.18, when the mods are still 9.17.1
9.18 is a special update really, since WG stated they would be using NA as a testing release, since it affects less people, if they fucked up, lol.