I know this is veering slightly away from the original direction of the thread, but a related item occurs to me.
Back in the '60's I bought my first "good" camera, a Miranda SLR and have since acquired other Miranda bodies from time to time. Those cameras have a shutter release on the FRONT of the body instead of the top as do most 35mm cameras. Tripping the shutter, regardless of which digit is used, is thus a matter of squeezing rather than punching. This, to me, has the great virtue of being a much steadier method and a more natural way of doing the job. Does anyone know why the front-button approach has never become a common one??? Incidentally, I recall that one other camera (Beseler Topcon, I think) was somewhat similar to the Miranda, with a front-mounted shutter button which angled at about 30 or 45 degrees to the body.) Wonder why almost every manufacturer, at least in 35mm, sticks with the punch-the-button-down approach?