the graphic artist ... believes artists have special dispensation from grammar rules (her words).

Oh, no they aren't. At least not in the newspaper business.
Artists and photographers are required to follow the rules and get their knuckles rapped by Editors when grammar rules are broken. Phojos write the cutlines (the bit under the photo) and sometimes there are cutlines under a graphic or IN the graphic itself.
As an aside, awhile ago there was moaning in TV from older news people that the "new breed" were sadly lacking in basic grammar and further moans that the reason was that the young people entering TV lacked basic training in newspapers -- where words and the rules ruled!
Now, I have heard, there is more emphasis on grammar and conciseness in many college courses in TV reporting!
This all comes with the caveat that the Older Generation always tends to bemoan the slip in current academics! And yet the ol' world keeps on turning!
All this not much help, but posts are sadly off because of the weekend and I am stuck inside by snow, with ice and sleet expected .. so I write!
Old Coot wow
wow