I don't know the ANSI system, but I just checked my climbing carabiners, they are KONG brand (italy, if that helps) and meet EN 12275
My nautical stuff has WLL or SWL marked, but no standard (broadly speaking I would be pretty happy to hang off most of it, and in many cases I have, although I prefer to hang off shackles rather than snap hooks)
I don't know the AS/NZS for climbing gear/carabiners (or same in other applications) off hand, but if this becomes interesting enough I can get my hands on it and see what the requirements are.
It occurs to me that I use ally hardware for random things that are not likely to go anywhere near load ratings, and steel for things where lives or equipment are on the line.
This has not been a conscious choice, and I rather suspect it has more to do with cost than anything else, I can afford ally clips and snaps for little things here and there, but the big end of town with the standards and the load ratings, steel is just cheaper, and mass is not a huge concern for me.
It's easy to overthink these things - sure for climbing, or belaying, or crane type activities you want a big factor of safety, but day-to-day, you can hang off an 8mm piece of steel all day and have no problems at all.