why do you think there is so much controversy as to whether photography is or isn’t art?

A fine art photograph can be as admirable as a fine art painting. A snapshot is like paint-by-numbers. Neither would be considered art. See the difference? By far, the largest number of photographs are snapshots. That tempts people to lump all photographs into the not-art category. Photographs are also tarnished by the capability of printing off many copies. In contrast, the Mona Lisa is unique. Somebody might buy a beautiful photograph. However, it's value is diluted by the possibility that the minute after the customer leaves the gallery the dealer could take another copy out of a drawer and put that up for sale. That there can be many copies helps some people describe photography as not art. Some photographers try to enhance the value of their work by announcing a limited print run.

Some people are narrow minded. They think of "art" as only being someone painting. The painter uses tools. Canvas, brushes, paint. None of it will create a painting by itself. The camera is also a tool. The best camera in the world will not create a great photo all by itself. Same with an instrument. Some people would not even consider music as art.

I have to add one thing though. I do cringe at photographs that are made to look like paintings with computer software. I would not have the damn gaul to hang such a thing beside someone's actual painting. So in THAT sense only, photography is not art.

Many people think all they have to do to make am excellent photo is:

a)Buy the most expensive (=best) camera

and b) Push a button

Honestly that can't be art