I decided to do a little research last night, specifically related to the NSW photo card and where it was (or wasn't) accepted as proof of ID. 

eg The Commonwealth Bank specifically lists the photo card (and other state's proof of age cards) as being worth 100 points in an ID check, i.e. it has as much value as a driver's license so you wouldn't need any other form of ID if you go into a branch to open an account or whatever.

But, on the flip side, businesses that do online ID verification (where sighting the card doesn't take place, eg via sending through a scan) often won't accept them because the reference number on the cards can't be verified digitally, apparently.

This Whirlpool thread gives some potential tips for making the NSW photo card number work in such situations, in some circumstances:

https://forums.whirlpool.net.au/archive/2644830