Another pod to MrsJWine.
You are in a job where you work with the public. That means you are going to get inane comments and silly questions. It's just the nature of that job. I worked in retail for years in high school and college. I got all sorts of comments and questions that were, among other things, bizarre, repetitive, answer-in-front-of-their-nose, rude, impossible to answer, etc. I had people who came to the store because they were lonely or bored or something, wanting to have long chats about their lives.
Mostly it's just a case of spewing out the first thing that comes into their head. Asking if you've seen the movie is a question they might ask anyone, a friend, coworker, etc. But because you are working there, there is even more chance you've seen it. Sure they are making an assumption that you see all of them since you do work there, but really, is there harm in that? Just say, "No, not yet." Period. End of conversation.
I get that it becomes irritating to get this question, but I think assigning some kind of malice to it or spinning it into your own personal experience is way overthinking it. Sometimes the best way to get through the day is to just smile and go along to get along.
Dealing with the public can be tedious and frustrating and annoying. But it can also be interesting and entertaining and challenging. So if you find yourself thinking of it in negative ways too often, it might be better to seek out a job (if possible) that has less contact with the public.