>> Who doesn't have open plan offices? There are about three people left in the tech industry these days who still have a private office.

There's a big range from true open-plan space (long tables with employees sitting shoulder-to-shoulder next to each other) to private offices with doors.

Somewhere in between are traditional "cube farms" which provide some amount of semi-privacy, less distracting nightlines, noise reduction, and feeling of personal space. Most of the companies I've seen are still more like this.