You can’t say there is no evidence of election fraud. This video shows exactly how it is done.
The thing to grasp is that the process corrupts the paper record of the vote such that a recount will produce the same fraudulent results as the initial tally.
Note, too, that because the tabulation is done electronically the results can be monitored in real or near-real time. This creates the opportunity to scale the fraud so as to avoid the risk of detection.