Given that
Japan has one of the most rapidly aging populations, I have to think the "no problem everyone will use an app" is going to run into some issues with the centenarian crowd. My mom is "only" 86 and she struggles with tech. She has a cell phone but uses it only when away from home or to call long distance, and doesn't use it for ANYTHING else but calling. If she was told every time she goes to the doctor or the bank or the DMV she had to open up an app on her phone she would not be happy.
Now granted the local (MAJOR, not a fly by night outfit) hospital's "authentication" is to provide your name and birthdate, that's it. I can't see anything stopping me from calling up and using someone else's name and birthdate to make an appointment, then showing as "him" and getting some nice expensive elective surgery and sticking him with the bill. You'd think they'd have better authentication - at least asking to see a driver's license or something - given that you could potentially generate hundreds of thousands of dollars in expenses, or create some embarrassing situations. By that I mean, what if a miscreant made an appointment to inquire about sex reassignment surgery under someone else's name? The fact of that inquiry is going to be in their medical records for the rest of their life, which could derail a marriage or career in politics. I mean, I suppose in theory it is possible to have something deleted from your medical records, but I'm guessing it isn't easy and there are no guarantees all traces of it would be gone.
So while I agree that Japan's rollout of ID cards seems to have been somewhat naive, there are some serious issues that can arise from the lack of proper identification/confirmation of identity. I'm kind of surprised what I outlined hasn't happened before (or more often, just because I haven't heard of it being done doesn't mean it hasn't happened a few times at least)