I have been a poll worker in the precincts at South Carolina.  Election day for the average poll worker is at least 14 hours long, and that does not include training sessions.  The pay is something like $75, and there are no lunch or other breaks.  I have also been a Republican volunteer in the days when we began to have Presidential Preference Primaries working the same amount of time for no pay.

The key to preventing fraud is to have workers who know the people in their precinct by sight.  If that is not possible, the photo ID is the key.  But, photo ID can also be faked:  Ask any college student who wants to buy alcohol.  Training, photo ID, conscientious poll workers are the key.  If not that, then try fingerprints or biometric ID.