In the last week or so I have been to 3 meetings and one training course. Every time, people have talked while a discussion is going on or while the trainer is talking. Despite being asked to stop they start again a bit later. It's not even as though the person running the meetings has ignored it.
I chaired a meeting today and had to ask about 4 times for people to listen while someone was saying something as they were having a chat about something else. It was only a short meeting and (if I say so myself) I am a decent chair who keeps this moving and wraps up as quickly as possible.
I just think it's so rude and can't fathom why people think it's ok.