I used to work for an escort agency as a booker/receptionist. Nothing sinister, no human trafficking. They weren't there against their will. Most of them were just strippers trying to supplement their income. That's not to say that all "escort angencies" are harmless, just sharing my experience...
Which brings me to this point- Part of my job sometimes was to find pictures for our ads, as we never used photos of our actual "dancers." This consisted of nothing more than going to a handful of different websites which contained VAST libraries of photos much like the ones we've seen of Kara. My understanding is that these GWC's (Guy With Camera, not legitimate photographer) sell their images (which they, not the model, own the rights to) to said websites. This is almost always the end purpose for these types of photo shoots. Where they go from there is anyone's guess. *
Long story short, I think people are reading way too much into her photos being on some agency's website. I think its just a very unfortunate coincidence, not a "cruel hoax" or any kind of clue/evidence. As far as wondering if she or her family knew about her photos being there, they would only know if - A. She or someone in her family liked to shop for escorts in Las Vegas and saw it themselves, B. The photographer was upfront/honest with her about what he intended to do with the images, which is highly unlikely, or C. If she ever decided to do some sort of reverse image search, and those rarely actually work in my experience. I can't think of any logical scenario where she, let alone her family, would know how those photos were being used prior to her disappearing.*
Just my opinion. Hope it makes sense.*