The marketing of the Brownie camera in 1900 marked the beginning of low-cost photography. Its 13cm make it rather similar in size to our phones, though it was considerably bulkier. But it was apparently considerably smaller than what was available until then, and of course its most important quality was its price - it was easily affordable to just about everyone, which is why just about everyone bought one.

It would stand to reason that the sudden appearance of lots and lots of people walking around pointing cameras wherever they wanted could cause more than a bit of discomfort. Wikipedia reports that the development of camera technology influenced the writing of the classic 1890 article by Samuel D. Warren and Louis D. Brandeis The Right to Privacy. But when the camera was a big, easily identifiable, box perhaps people responded differently to being photographed than they do today. Today, though we hardly notice the camera, we seem to be aware that someone, somewhere, is just about always pointing a camera in our direction and clicking. Many people find both that fact and even the thought of it disturbing. And the literature devoted to the etiquette and the ethics of photographing strangers started by Warren and Brandeis continues to grow. It's a good guess that part of the demise of Google Glass was its miniature, almost unnoticeable, camera that made people hyper-sensitive to the possibility of being surreptitiously observed.

Tourists are, or at least used to be, easily identifiable - they were the people with cameras strapped over their shoulders. Today, however, when everybody has a camera, and that camera is in almost constant use, it's hard to distinguish between the tourist and the local. The Brownie may have initiated tourist photography, and its descendants have made all of us into tourists even when we're at home.