Good question… I guess if someone created it, it’s a work of art. But if it’s on a wall in a public space with no attribution, does that mean the artist has effectively given permission for it to be shared without attribution? What about murals in cities such as those in Christchurch and Hamilton and Dunedin? Maybe these artists rely on photographers taking photos and sharing them on public online platforms for free advertising of their work?
I would rather be safe than sorry and do try to give credit where credit is due whenever I can. I have fallen from grace from time to time but where I know who the person is that worked on something I try to acknowledge them- out of courtesy if for no other reason.
I think there is a difference between public art and art in a private space. I do photograph murals, try to credit or give a link to more info – but when something is out in the public it is meant to be enjoyed and shared.