Mirror, mirror on the wall this morning?

From passport or national ID card, your post is now shifting the goal posts to "proper ID", whatever "proper ID" means?

It is not absolutely illegal to cross a Schengen-Schengen border without a valid passport and/or national ID card. The laws and regulations and court rulings applicable to matters of these sort are absolutely not even all uniform across all of the Schengen Zone and it's all specific circumstances based -- as anyone with actual legal knowledge of these matters ought to know by now.

The "think of the women and children" type appeals don't move me in this context. Rapists and other criminals get duly arrested even when not crossing borders and not holding a passport and/or national ID card; same is possible when crossing borders without their valid passport/national ID card.

ID is not security; but if you want to make an argument about why you believe ID is security, then try to make a coherent argument in an effort to prove my statement false; then we can discuss that.

This thread is about flying within the EU without a passport (or national ID card) -- something that is readily possible for intra-Schengen travel when knowing the route, airline and checked baggage situation relevant to a person -- and it is not absolutely illegal. Rather it is only illegal under some but not all circumstances for intra-Schengen travel by air; and it is absolutely legal under other circumstances for intra-Schengen travel.

If someone is so afraid of people flying without showing their own valid passport or national ID card to fly -- something that happens very frequently without incident every day -- then why not a big welcome for sunlight, a great disinfectant, shining on what there is and should be in plain view?