I have used a ton of touch screen devices in public. I've encountered quite a few that were miscalibrated.
Public devices put up with abuse that your private devices do not.
My kids abuse my iPad pretty heavily but generally smacking on the screen with their hands and fingers a lot but I still have never seen it mis-calculate a touch.
I don't know much about electronic voting machines but I wouldn't be surprised if they mostly used resistive touchscreens (which are historically much cheaper to produce).
I recently had to help my mother recalibrate her sewing machine's touch screen.