Why reported challenges with touchscreen voting machines don't signal election rigging

The reports erupt on social media every election year: Voters say they tapped a candidate's name on a touchscreen voting machine, only for the wrong person to light up as their selection.

With some trial and error, and occasionally help from poll workers, the voters are generally able to cast their intended ballots. Nevertheless, some come away from the experience assuming the worst — that the anecdotal issues are proof of a partisan election-rigging scheme.