[mootothemax]

Oddly, that's not true. A passport is necessary to get into a country, not leave one.

Not true for me, at least. I live in Poland, which means I get passport-free travel (and ID-card free, for that matter) within the EU Schengen Area, but not when visiting my home country, the UK, since it's outside the Schengen area.

To visit the UK, I have to go via the scary ladies and gentlemen in glass booths with big guns strapped to their sides and show my passport (or ID card if I had one). I've travelled a few times to other countries outside the Schengen area, and each time the only way to get to the gate is via these booths. I'm pretty certain that there's no opt-out.

Poland's not alone in this; plenty of countries check your passport on departure. Last one I remember is Turkey, pretty sure when I was in India and Tunisia similar happened.

[atirip]

That's because governments are widely agreed that the "sender" country is responsible if passenger has no right to enter "receiver" country. So to avoid the hassle, it's mandatory to check your passport when you leave Poland, but not whether you have right to leave Poland...