ID card options if you don’t want/have a driver’s licence

So, following-up yesterday's post. A little research on IDs for young adults (in particular to prove they are over 18) who don't drive led me to two possibilities -- assuming one doesn't want to carry around a passport: Keypass -- $55, and supposedly recognised nationwide. Proof Of Age card -- $10, and also apparently recognised throughout Australia. It seems other states have similar