[krzyk]

Why carrying it is practical? What is it used for?

The only time I need my ID is during elections, but I can also show the one I have in our government produced app.

Older people in Poland do carry those, mostly out of some kind of habit and some kind of fear that police might need it. I can drive a car and get a speeding ticket, and all I need police to know is my ID number (it is not the identifier of my identity card), which I know by hard, it consists of my birth date plus 5 semi-random numbers). I don't need my ID, my driving license nor my insurance data - everything is located in police database based on my ID number (or my license plate).

Bad sides of carrying it is that you might loose it, and that is a PITA, because you need to block it right away (someone might take a loan with it, happens I kid you not) by calling your bank or similar service.

So I take it out from my wallet (which I don't carry also) only when I go to the airport.

[hermanzegerman]

Because if you speed and Police can't verify your identity they will take you to the station to verify it.

Same thing if they stop you for whatever reason and ask you for it.

Or your personalized public transport season ticket is only valid in combination with a government issued ID.