I have this problem all of the time. I frequently have to triple or quadruple tap. Why is it so often unresponsive? Is there another function that double tapping serves? It would be pretty hard to accidentally zoom so that can't be the issue, they need to increase the sensitivity of it. It's a pain to have to switch hands when youre holding it in your main hand so you can pinch zoom. It's much easier to do it with your thumb when you are browsing one-handed, which is what most people do.