Heck, the stupid Windows application for the "my number card" has this problem, and it is an official application coming from the government itself! How is it possible that in 2024 we still have this problem?

For the record: this happens because text encoding problems was solved by broad adoption of not Unicode but by localized Windows 9x. Windows NT and apps on it to this day uses whichever encoding used by equivalent ancient regional versions of Windows 95 for language/region it booted in, e.g. cp1252/ISO-8859-1 for American English and cp932/Shift_JIS for Japanese.

True unification into Unicode only happened during the mobile shift in the form of iOS/Android.

Between 2010 and 2020 I've ordered something from Amazon around 5 times, and each time they spelled my legal name wrong, each time in a different way (due to encoding issues). And I'm an european, living in a large country. So I'm not surprised CJK languages have this problem.

Yeah and a part of e-tax literally asks you to have Japanese Windows in fine print or it fails silently without any warning messages (Fixed by changing chrome locale to Japanese thankfully). Gotta love Japanese websites. I just go into the office and hand write the forms because it beats trying to debug cryptic issues.

Many Japanese PC games and desktop applications aimed at the home market, from small to large developers, also do sort of these things. Just look up the word "AppLocale".

There is a system wide setting that changes all non-Unicode text encoding to another code page e.g CP932 for Shift-JIS. Third party tools are available to do the same conversion on a per application basis.

It’s not as bad as trying to load some really old CJK web pages on mobile devices: few mobile browser has an accessible option to select character encoding and there appears to be none on iOS. The only option is to change the system language and that didn’t always work for more obscure character codes.