Plagiarism in Photography

There has been a bit of talk on The Online Photographer about photographic plagiarism. I don't think this is possible. I remember in photo school, one of the studio assignments was to find a photo and recreate it. It was a lesson in lighting, composition, and large format technique (ok, it covered a lot of bases...)
I learned a lot from this... It is surprisingly hard to copy a scene. First you need to analyze the camera angle, depth of field, lens etc. Then you need to analyze the quality and direction of light. It is not a trivial matter to recreate the scene.
I also found out that "copying" someone else is a good starting point for your own creativity. For the above assignment, I made a completely different photo that reflected a lot more of my own personality.
This brings us to the root of my argument. Photography as an art form reflects the personality of the artist/photographer. No two people have the same personality (ok, some people have the same lack of personality, but that is a different problem...).
Now, outside of the studio, in the "real" world two photographers can be standing in the same spot and see different scenes, I am sure we all have experiences here. I remember shooting with a friend. We both stopped at the same scene but we only had one sheet of film between us (we were sharing a 4x5 camera). We both agreed on placement of the camera, but I saw a vertical, while my friend saw a horizontal. We shot wide and later in the darkroom printed our individual crops. They were both strong interpretations of the scene.
but lets assume, for the sake of argument that two photographers see the same scene, or it is a well photographed scene. Why are these two photographers shooting the scene? At the risk of sounding like a bad art critic, what is their motivation? If the motivation is just to record the scene, what exactly is being plagiarized? the scene itself? If the motivation is to emulate another photographer, where can you draw the line between plagiarism and learning from a master?
The cliche about imitation and flattery comes to mind.
There is also the adage about nothing new under the sun...

But now we get to the legal aspect. I am not a lawyer, and I have not discussed this with anyone with legal knowledge, but my opinion of the situation is this: If you have a great photographic idea, and I copy it and I make a ton of money from it, where do you stand? Should you get a payment from me? Why? If the original idea is so great and worthy of recognition (by cash or fame) why did you not profit? Art is not like other commodities. You cannot undercut price, each creation is an original. (I am not talking about re photographing other prints, which would violate copyright) If I am a better marketer than you, should I not get paid better? If I refine your idea closer to my ideas, should I not benefit?
Now, if the images are so close, such as some of those in question, then I argue that the photograph is just a recording of the original scene and doesn't have any intrinsic value. Anyone could come by and capture the image.
Photography, in my mind is about extracting the essential elements from the world around us. These essential elements vary according to the message we want to say. If your message is, "I really respect Edward Weston, and I would be honored to try and emulate his approach to photographing peppers", great. If your message is "I think that photo is very banal and simple to copy", is your opinion less valuable? Your opinion may not be popular, your opinion may be naive, but one of the huge values of art is the possibility to have your own opinion.
So is plagiarism possible in photography? Is plagiarism possible in opinions? Can you really copy a true piece of art?