What if you don't have a passport?
This is within the EU, so obviously what would be asked is an EU id.
There isn't one. Ireland also doesn't have a national ID program, so effectively for most people their passport or driver's license are the only forms of government ID they _might_ have. But even then it's not mandatory to have either.
Now I just noticed that although the subject is "most of the EU", this is an Irish site, so maybe they just didn't really take this into account.
A friend was talking about how their US friend got given a sex offence label due to downloading a zip of porn that unknown to them contained some CSAM. Lost their job and worse.
You didn't know is no defence in some jurisdictions. You personally can't check images or image collections for legality, so the risk is real.
Maybe add a couple more paras to your comment?
If you give me six sentences written by the most innocent of men, I will find something in them with which to hang them.
- powerful political figure (1585 – 1642)