My "cash" or card transactions has gone down manifold over the last couple of years. Everyone, including roadside vendors, accept mobile payments that's enabled using UPI (unified payments interface) that's tied to my bank account. There are dozens of apps and "wallets" that use it, including Google Pay, Amazon Pay, Paytm, PhonePe, etc.
My income tax records are all available online, and "filing" is a matter of importing this data using a tool that the income tax department makes available on their website, checking the pre-filled forms, and pushing the "submit" button -- signed using an Aadhaar number enabled OTP.
Vehicle rego can be checked in the app so I can see my expiry and get notifications when renewal is due. We haven't had to attach any physical proof of vehicle registration since 2011.
The app can be used as proof of digital licences for boats, cars, trucks and for occupational licences (builders, tradies, security) since 2017. I can also view demerit points. Also does proof of age and more recently COVID checkins. The app was locally developed. I think most states here have similar systems https://my.sa.gov.au/
The inspection itself isn't anything complex I think they check brakes, headlights and such usually takes about 20 minutes I drop car off go and grab a coffee and it's ready when I get back.
Once the inspection is done everything else can be done online.
I don't mind the process so much (I only own 1 vehicle and live in city) but my parents for example live in a remote location (50 minute drive to get to mechanic) and have multiple cars, a boat trailer and a regular trailer which all have the same registration date so for my Dad it is pretty much an entire days adventure to get all the various inspections done.
Nearly everyone gets their car serviced regularly every 6 to 12 months and they risk being defected if driving with a fault. My guess is a comparison of road safety outcomes between states would show very little benefit as the other states haven't leapt in to follow the example.
I remember paying my SA car rego with laptop over Maccas wifi in Devonport after rolling off the ferry sometime in the naughties. We didn't do it with our phones because they were still potatoes.
Like the US it is a federal system and states have constitutional authority over road rules, registration and licensing and can do their own thing. Every state has its own websites and apps for these things. Half our states do not have digital licences yet but some of them will be ahead in other areas. I suspect if we had to wait for something national to happen the less progressive states would hold us all back.