Exploit and Click:
Photography tends to magnify and distort both deeds and misdeeds—more so than other art forms, and in fact more than almost any activity I can think of. The specter of exploitation hovers over it, and it's this, I think, that accounts for Hawk's disproportionate outrage. If Greenberg were making infants weep in the service of a psychological experiment, one might feel uneasy, but the dismay would no doubt be tempered by one's sense that a greater good was to come of it. If she were doing it because she wanted to, say, draw them, or write poems about them, many people might still find it objectionable, but not, I don't think, to quite the same degree. Indeed, if she were doing it just for the hell of it, we would consider her cruel and culpable; but the fact that she made them cry so that she could take their pictures somehow makes it worse.
The point becomes clearer, or at any rate starker, by comparison with pornography. In most states, the age of consent is 16 or 17, but federal law stipulates that you can only be photographed having sex if you're 18 or older. Two 17-year-olds can copulate to their hearts' content, and their friends can watch: However creepy it may be, no laws would be broken. But they can't be photographed in the act, nor can anyone, of any age, so much as look at such a photo. The picture has a legal status quite different from the thing it pictures.