Having just traveled to Europe and soon returning I can verify that I did not see those signs but I complied with the panopticon. I had already heard that it was voluntary but I didn't care because I was into a long trip.

Kind of the same way I forget to take it my pocket knife and I remembered in the security line that I should have put it in my baggage. I just pulled it out of my pocket and showed the security guy and I told him to keep it out throw it away.

My saving grace is that I'm fully compliant with the Supreme Godhead and the atheists who "invent" this nonsense are clowns serving themselves. They are not in charge, never have been and never will be.