I think the difference between a public place and an office is that it's really unlikely for any of those strangers outside of an office to interrupt your work. In an open office, every conversation and set of footsteps feels like a potential disruption.
Yes, I think this is the difference. The noise around you becomes background/white noise.
But honestly, I don't know how you can work in these areas. Doesn't it prevent you from making phone and conference calls? Assuming yes, maybe that's another reason you can become more productive.
For my part, I avoid phones anyway - which seems more commonplace than I'd imagine, amongst other technically-minded sorts.
I love open cube "bullpens" for a team of 4-5 people working on a shared goal, but a completely open office where anyone can disturb you has given me issues in the past.
* Exaggerated a little, I'd probably drive myself nuts in an office alone.
Totally agree, on days when I WFH, I drive my wife a bit crazy in that I like the TV on, yet get a bit perturbed if she interrupts with something not too important. :) The TV eases the pain of silence and does not require me to answer it. At work, there are at least a dozen direct potential possibilities for someone to interrupt me at any moment.