Yes, I've tried setting Play Store to never automatically update apps (I even have Wi-Fi completely disabled on my phone, just in case, although I have Play Store set to update apps only over a "normal" data connection — no big loss, as there's not a single useable Wi-Fi in my vicinity), and while this does seem to be effective for most, if not all, of my other apps, it seems to have no effect where Play Store itself is concerned. It will still go ahead and happily update itself regardless of the settings.
Is Play Store just a "special case" that is simply impervious to any attempts to restrict it from updating itself? Could there possibly be a deeply hidden setting buried somewhere that doesn't appear in any GUI tool?
As I said, disabling all updates, or disabling only Wi-Fi updates (with the phone's Wi-Fi disabled) in Play Store has no effect when it comes to updating Play Store itself. While this just seems plain wrong to me, perhaps it was intended that Play Store should always ensure that it's running the latest version of itself (and indeed, there may be some good reason for this), unless there is, in fact, some hidden switch somewhere to override this default behavior. If such a switch does actually exist, I'd sure like to know where it is!
Thanks for the reply, by the way. Appreciate it.