Do you have a source for that statement? In Germany, ballots are counted by people making tally marks on paper.
Edit: Here you go. I couldn't find research or a study regarding it but this is probably good enough and was always my experience when I voted by paper: https://www.wired.com/2016/11/vote-counts-ballot-get-counted...
Edit: Here you go. I couldn't find research or a study regarding it but this is probably good enough and was always my experience when I voted by paper: https://www.wired.com/2016/11/vote-counts-ballot-get-counted...