The nice thing about scanning either by the voter or while the voter is present is that spoiled ballots - by stray, faint, or partial marks, or overvoting for t

The nice thing about scanning either by the voter or while the voter is present is that spoiled ballots - by stray, faint, or partial marks, or overvoting for too many multiple candidates - are reduced to near zero, and are replaced by fresh voter-marked ballots, which simplifies all later tabulation, and reduces confusion and challenges about mis-marked ballots, thus increasing voter confidence in the whole election process. Anyone who is interested in election processes should volunteer to work an election, either helping operate a polling place, or as a poll watcher, or similar. This is one of those areas that looks simple, but has a lot of difficult edge and corner cases. I've been a poll worker and a registrar of voters, and it is not as simple as most people would think.