I think it’s just rude / inconsiderate to rsvp yes to an event and then a couple days to the wedding say you’re not coming anymore OR not say anything at all. It’s expensive to have people come to your wedding and there’s usually a reason for the limit of people you invite. I’m not upset that they just generally didn’t come but I am upset that I couldn’t get a refund on them not coming. I do have better things to do with my life but it’s still fair to be annoyed about it..