Some probably didn't, and most certainly do not know about how horrible it was. So of course that movie would affect people---hell it affected me when I saw it and drove me to learn more.
Same with movies about trafficking. When good movies are made people get into it, they get to know the characters beyond words on a screen, they see people instead of numbers and statistics, and it moves them to learn more or makes them more aware. It was films, documentaries, and actually seeing aborted babies that opened my eyes to the horrors of abortion, which was something I already "knew about" , but didn't really know about.
.I don't know why you find this so surprising. Wait, I know you actually don't, you're just angry. I shouldn't be wasting my time.