Earlier quoted context omitted.
Exactly. If you're sitting in a restaurant eating with some acquaintances/friends, you shouldn't expect privacy there either. The table next to you can get offended with some random inside joke that includes the words "penis", "boob", or maybe even "yoga pants." No jokes allowed unless you're wrapped in a Faraday cage filled in with sound proof material. None whatsoever.
That analogy is completely ridiculous. Restaurants are not venues that require customers to agree to a code of conduct barring inappropriate jokes. They're also not the kind of places where people are sitting quietly and near enough each other to hear jokes told quietly.
I've been to plenty of conferences and I haven't heard of this happening, except to politicians when they forget there are microphones and news reporters around.
This is why our society does, in fact, have a separate set of privacy rules for people classified as "public figures". So the rest of us can hang out and chat in comfort by assuming in all probability the absence of a news reporter or papparazi trying to play "gotcha" with a camera and microphone.