How much else do you know about it? At every level, there are machine checks and human checks that must agree, or an audit is triggered. In the event of dispu

How much else do you know about it? At every level, there are machine checks and human checks that must agree, or an audit is triggered. In the event of disputes, audits are transparent, conducted by non-partisans, and observed by partisans (from both sides). There are exit polls and other independent surveys that would further indicate a large deviation that merited further study. There isn't one single layer that prevents fraud. There are many layers, meaning it would take an astonishingly coordinated criminal organization (like many hundreds of thousands of people who are all able to keep things a secret) to change the results in even one single state or large county. It's much cheaper and easier to just try to win the election fairly.