> For some people the idea of chatting someone who's sitting 5 feet away from them is super weird.
This is exactly what happens in my employer's "pod rooms." There are 10 of us and inevitably someone will be all, "Jack; Jack!; HEY, JACK!!" and someone else says "he has his headphones on just send him an IM" and the first person replies "ugh!" and then gets up to walk over and stand at Jack's shoulder until Jack takes off his headphones and looks up at the person.
It's not just one person that does this or we might could get the behavior to change. Apparently humans in group spaces just really, really, really want to verbally speak to other humans in those spaces and there's no amount of "hey guys I'm really trying to work here could you keep it down" that doesn't come across as rude or condescending.
I guess part of it for me is there seems to be no escaping from the noise of life any more. At least at work I used to have an office with a door that I could close for a couple of hours of solitude and heads-down real work. Now, after the building redesign, there are 950 people in the building and a pittance of conference rooms and phone rooms and "team rooms" (little conference rooms supposedly shared between just two or three teams sitting in larger "pod rooms" but, in practice, squatted in by one or two people all day). I've spent twenty minutes walking around my building and the adjacent one just trying to find somewhere to do a phone screen for an interview candidate.
Combine that with the rest of the world getting louder[0] and it's becoming a little frustrating.
0 - Right now I can hear my neighbor upstairs walking around on the hardwood floors all of our apartments have with his hard-soled shoes like he's been doing for the past hour, the traffic outside because apparently density should only exist next to busy arterials in the city where I live, planes loudly going overhead because the cloud ceiling is lower and they're taking a more direct route to the airport, and now the backup generator for the newly-constructed senior home is running its weekly test.