Certain updates/upgrades don't seem to be downloadable from Apple's Support-Downloads page; in fact they don't even show up. I refer to things such as Safari 6.1.2 and Mac App Store Update, which show up under Software Update but nowhere else.

I prefer to download stand-alone dmg files so that I can install them at my discretion (not replace what I already have). That does not appear possible under the present Apple regime.

I do note that these are available "off-site", but I'm not sure I trust third-party sources (eg, Softonic, Macupdate).

Anyone got a clue what's going on?