Title is self explanatory.
Living in the US for several years, I noticed that more people choose to audibly burp, even more so if they are familiar with you. Because I would just try to keep it in my mouth and make little to no sound, it was surprising at first when there won't even be a word of "sorry," or anything. I no longer take offense to it of course because a lot of people just…do that.
I mean, yes, its a natural thing that happens to everyone, but in Korea, it would be a bit rude and disgusting to burp out loud even among people you are familiar with, but it seems like its less of a problem in the US, so I was curious. Its a small thing, but I get reminded of it every so often.