It’s such a cliche, the writer sitting at their laptop in a cafe, working on a novel… I think the general idea is that writers write in cafe’s to be seen writing. The truth is that being a writer can be very isolated, very lonely. You work alone, without human contact most of the time. In my case, I also live alone, so there is a lot of alone time in my life. Working in a cafe is a way to remind myself that other people actually still exist.
Also, it’s a change of scenery and a way to see other people, to observe them. I use observation to build characters. If I stop seeing other people suddenly everyone will become literary clones of me or will have the exaggerated mannerisms of TV and movie characters.
As to being seen writing, only once in my life did I write to be seen writing, and it was specifically to fulfill a stereotype. I was in Paris and I was writing in a leather-bound notebook in a cafe. I made a point of that, because it was just too good a stereotype to ignore.