I really don't know how I have escaped showing the passport (without any effort on my side).

It's reasonable to ask for mine (to check that I really am who I am; although it would be hard to imagine how somebody could access my reservations, print them out and be ready to pay for the room) but asking for the documents of all the guests is unreasonable, unless you visit a police state like Russia, where they have to register every foreigner living in a hotel.

Uh-oh, the same old argument again. I have nothing to hide; I have something to guard - my privacy. By your definition strip-search by police in the middle of the street is OK - after all, you have nothing to hide, right?