Honestly curious - what kind of abuse could cause a calibration error?

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.

iPads used capacitive touchscreens which aren't prone to the same sorts of calibration issues that resistive touchscreens are.

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).

iPad uses a capacitive touch screen. Older technologies are very prone to mis-calibration, even if they are not in heavy use.

I recently had to help my mother recalibrate her sewing machine's touch screen.