it's quite simple. Does a camera capture and reproduce the 3d effect of oil paintings, or reproduce a 60meter sculpture? No it doesn't. So it isn't the same. No, taking a photo of a photo depending where said photo was, would be like copying a picture from deviant art or filming a film.
As for street artists, why do you keep banging on about that, if they do art in a public place they have no rights, however you do have legal rights to film and take pictures in public places. So please drop that point. It's pointless.
If you are getting as pedantic as "3D effects" of oil paintings then I'll be pedantic and start talking about the sound effects, 3D and size of a cinema... I see where you are coming from but for a large number of paintings it really makes little difference, which is why people buy so many prints from galleries and why so many people have prints up at home as main feature art in their rooms.
As for the street artist, there were a number of reasons I wrote that. Firstly that gets away from the permissions issue you may have in a gallery, secondly they have the same copyright rights as the art in the gallery (as mentioned previously in the UK content creators have automatic copyright of things they create, the main difference is the permission to photograph issue, which isn't the same as a copyright issue). Thirdly it was to show that big companies and small single man bands have the same rights in the UK. So no I'm not going to drop it, it is an important part of the argument.
You believe they are all different, and believe some should be criminal, yet those same laws would have to apply to tourists taking photos of artwork, just as they do to people camming in cinemas and copying other work done by big companies. As soon a they start making money from that copy is another matter entirely however.