Really? What is the definition of "probable cause" in his state? I am not a lawyer, and, if I understand correctly, you are not either. I don't think either of us can make an assessment of what the police-officers at the time determined to be 'reasonable'.
Please tell me that this statement was meant to be tongue-in-cheek. Comparing a modern-day policeman in the US asking someone what they're doing on a bridge late at night to Nazi-era Germany is ludicrous. I would suggest that you head down a local retirement home and see if you can find someone who might have lived in Berlin, Dresden, Hamburg, or other large city and have them describe for you what life was like!
Legally, unless you are driving a car, you are not required to carry ID in Canada or in the US. I would venture to say that any state laws to the contrary would violate the American Constitution. Since you are not required to carry ID, you are not required to show it. I was once stopped by provincial police in a car full of people that was driving up the highway sideways in what the police would have considered to be suspicious circumstances. They impounded the car but the only ID they asked for was the license, ownership, and insurance of the driver.
If they arrest you they can ask for ID, but even then it can be a "John Doe warrant" but without a charge the arrest won't hold, since taking photos is not illegal.
If more people stood up for their rights like the photographer in the film, there would be LESS harassment of photographers by the police.
skieur