Why do you need to know that though? Most people in the US never leave the US. I mean, if they don't need to know it, why do you care?
Sure, I encourage knowing stuff, but I'm not going to think it's bad for someone to not know something that doesn't matter to them. If they don't care, then that's fine. Why should you? Do you care that a lot of people don't know a lot about basic physics?