It really depends. I can imagine this incentive was started because either employees came across images and didn't think much of it, or dismissed it because they didn't want to deal with the hassle. The article mentions a picture of a naked child; didn't mention any abuse or sexual acts, so it could be the owner's own, I mean just look at how many naked baby pictures are out there. It's a gray area then. With this incentive, it was reported; without it, the employee may have shrugged it off. I think they're incentivising "better be safe than sorry" with some monies.