[codedokode]

This is an internal passport (not for travelling abroad) and everyone has it because without it you cannot buy a train ticket, open a bank account, enter the college etc. Also there is a fine if you don't get it when you are 16 (or 18, I don't remember the exact age).

Also, young people cannot buy alcohol and cigarettes without it (to prove that they are adult) so some of them are motivated to get it as soon as possible.

Here is a Wikipedia link in case if someone didn't hear about "internal passports": https://en.wikipedia.org/wiki/Internal_passport

[codedokode]

Also I wanted to add that internal passport is valid for a long time and you have to change it only twice in a lifetime: you get it first time at 14, then get a new one at 20 and at 45 years and that last one is valid forever (of course if you don't happen to die). So although there is a fee to pay, it is not really expensive.

[tsbertalan]

Why should you need any form of identification to buy a train ticket? Say, for domestic-only travel.