Japan has this too now, but it's pretty new and not required so not everyone has one yet.
If you do have it, you can use it to print super official documents at the convenience store and pay your taxes online (if you get a chip reader for your computer).*
*I know in the US you can pay taxes online with just some personal info for verification, but for some reason Japan is super serious about verifying online financial transactions.
I never understood why official institutions are so concerned about verifications when you're the one giving them money? And they all do this, the same thing is here where I live. I understand the need for a positive identification when you're buying something, but for paying taxes? What, someone will go around and pay other people's taxes? And even so, why the government cares, as long as it's paid?
It's not actually for paying taxes, it's for filing taxes.
If someone filed a fraudulent tax report in your name you could be liable ("I made zero dollars last year!"). Actually paying the taxes can be done in cash anonymously at a post office bank teller (or at a convenience store for municipal taxes)
https://en.m.wikipedia.org/wiki/Estonian_ID_card