Those arm positions occur over the course of a fluid motion in a single second. How long does it take for you to drop your hands to your side or raise them to clasped from the side? It doesn’t take me more than about half a second as a deliberate movement.

It takes you several seconds to move your arm? I hope you don’t do manual work.

Also did you use the iOS camera app before? You can see how long it takes for the iPhone to take multiple shots for the always-on hdr feature, and it isn’t several seconds.

There's three different arm positions in a single picture. That doesn't happen in the blink of an eye.

It's a lot faster than you might be expecting. I found it helps to visualize it in person. Go to a mirror and start with your hands together like in the right side mirror. Now let your arms down naturally, to the position in the left side mirror. If you don't move your arms at the same exact time, one elbow will still be parallel to the floor while the other elbow has extended already, just like in the middle position.

Thus, we can tell that the camera compiled the image from right to left.

I can also see the three arm positions being a single motion, just in three different time frames. If it really takes seconds to complete a composite, then it should also be very easy to reproduce, and not something so rare it makes it into the news. If I still can't convince you, I guess we agree to disagree then.