Studies have found that machine scanners are more accurate than hand counts. Local election officials also say hand-counting ballots would require more time and resources.
Researchers in a 2018 study comparing two statewide recounts in Wisconsin found that, “Scanning paper ballots produces a more accurate election night count than hand-counting ballots.”
An older study looking at New Hampshire elections between 1946 and 2002 found a 0.5% discrepancy between initial counts and recounts for scanned ballots, but a 0.9% difference for hand-counted ballots.
“Republicans are arguing that humans are more likely than machines to get the count right,” wrote Massachusetts Institute of Technology professor Charles Stewart III, who runs the MIT Election Data and Science Lab. “Evidence however, suggests the opposite: Computers — which ballot scanners rely on — are very good at tedious, repetitive tasks. Humans are bad at them. And counting votes is tedious and repetitive.”
Election Law Journal: Learning from Recounts
Washington Post: Why do Republicans want to ban ballot scanners?