This is largely the consequence of the Windows API having a built in option to use these buttons, without having an option for custom text. It would be a lot more work to build a custom window with custom buttons than just callong this API.

https://learn.microsoft.com/en-us/windows/win32/api/winuser/...

You could set a custom text by sending WM_SETTEXT to the respective button. It wasn’t a recommended practice, though.