You don't hide the ID number, you show the card itself. In slovenia (and other former yugoslav countries) we have a unique ID for every person here.. It's set

You don't hide the ID number, you show the card itself. In slovenia (and other former yugoslav countries) we have a unique ID for every person here.. It's set up from the date of birth (0101021 - 1. jan. 2021), then two digits for the foreign yugoslav state (50 for slovenia), then a tri-digit counter for each birth (first person born that day is 001, and so on), and one digit for the checksum, which can be easily calculated.... so basically, with a calculator and 2 minutes of typing in the numbers, you can calculate a valid ID number. But to open a bank account, you show the ID, which has any-copying measures (like money has), a photo, a serial number (to be cancelled if stolen), and only then the bank creates a new bank account for you. You can also use the same card to buy alcohol and travel through many european countries (no need for a passport).