I wouldn't say they are sold specifically for being pets. They can be, but owls don't make good pets, and most people won't ever look how to properly care for them. If they were that invested in owl welfare, they wouldn't try to keep them as pets, but I digress.
There are many parts of the world where owls are not revered. Many beliefs still exist where they are some kind of supernatural manifestation, and their bodies either hold mystical properties or they are embodiments of the underworld. I won't go too much deeper into it because it is depressing, much more widespread than most people would believe, and with it covering so many parts of the world, there are a lot of things I have no experience in and I don't want to let my fondness for owls take over and start maligning large groups of people as a whole.
There are many raids worldwide for animal trafficking of all sorts. Here are two semi-recent raids in South Africa, this one mentions Owl Rescue Centre, but their feed has many such stories.
Here is an Audubon article about Africa and one from a conservation society talking more about India about the many people and many reasons why these animals get trafficked. They do get a bit grizzly, so be warned if you check those out.
I think it's important to know about, and I read most of these stories I come across, as well as seeing and learning about rodenticide, lead poisoning, and all the other human based hazards out of a strong desire to combat those things, but it's painful to see, and I don't expect most of you want to know that level of detail, so I will kinda hint at it occasionally, and if you guys ask questions, I will share more. I'm mainly here for cheery stuff, and I find things like this story uplifting because the focus is more on the good people doing the rescues than the tragedy that was awaiting these beautiful birds. As predatory animals, they reproduce really slowly, so each one taken from the wild has a wide ripple effect.
That probably is more than you wanted, but if there's anything more you want to know, just ask! I'm up for talking good or bad about owl and wildlife rescue and conservation.