Basically she means that a documentary photograph isn’t always 100% true something else could’ve happened in the time the photo was taken and it made it look a different way . and he’s photographs can convey a larger meaning than what is present because you could take a picture of something and not know the full meaning behind it .
I agree with what’s above also it’s kinda like this on websites I’ve read multiple documentaries about different things and I come to find out that a they never happened or b I was all incorrect information