Hi there. Thanks for more background thoughts. I hope readers are enjoying our back and forth.(I'm a former musician, a current professional artist and commercial photographer, the former designer and manager of the jurying process for the NEA and NYFA Visual Artists Fellowships Grants programs, a photography graduate and teacher, an art critic, and a director past and current on the boards of four arts organizations. So of course I have a perspective that may not be shared by most people experiencing photography.)
1. The idea that the status called "art" is "contested" is neither new with photography nor especially distinctive to it. But I argue that it is a problem only for those who, as you said yourself, don't perceive enough cues to be artistically affected. Traditionalists infamously believe that the limitations of their experience are the measure of everyone's experiences.
2. If you are an artist, and you want to use a camera to create your image, you generally use the camera to select, compose, and rhetorically shape and tone forms within what is going to be the display area. If you want a print, you coordinate those decisions with the options afforded by the printing material to exercise exactly the same controls. Teaching art to photographers does not necessarily induce them into photographic art-making. Teaching photography to artists almost invariably cultivates artistic photography.
3. The labor involved in street photography involves selection of subject matter, pursuit of persuasive point of view, balancing of graphic effects, and anticipation of interpretation. All of these cohere as skill that is exercised as a real-time performance of competency, just like speech (the Saussurian parole not langue) or instrumental free improvisation. But audiences' actual familiarity with most street photography is akin mainly to either theater or iconography, which is exactly what characterized art painting in the 16th century except that the implied and depicted narratives then were mostly religious instead of secular. This doesn't require a paradigm shift to occur in the 20th and 21st century. It requires education and actual practice.
4. I think you meant "found art" not "found photographs", but whatever. Anyway, your concluding assertion is false. Example: western culture is rife with myopia when it comes to recognizing art that is made outside of western traditions. The inhibitor is tradition-based expectation. Luckily, anthropologists have been able to weigh in on everything from cave carvings and pre-Columbian pottery glyphs to eastern ancient stone monuments and ink blots. This enormous stock of "found" art surfaces because of the ability to associate the aesthetics with the cultural practices of the originators. Photographs are a real latecomer to the universe of materials that readily go under such artistic interpretation. The good news is that artists, curators, teachers and historians are a big enough community to identify what it is in photographs that provoke an artistic experience. Meanwhile, the enormous proliferation of photographic imagery doesn't compel any of it to generate an artistic experience any more than the proliferation of cooked food compels it to represent culinary expertise. There's no "problem" here, there's an opportunity.