Those are mostly volunteers. The work takes multiple weeks so a big proportion of the volunteers are retirees because people with jobs can only help during their free time. The work itself is physically demanding: preparing the venue, preparing the ballots, sending out invitations, then right after the election is closed, there is an expectation to finish counting and report the result on the same day because everyone is itching to know who’s the winner, so in large neighborhood the volunteers might not be home till morning. Also, in this election you cast 5 ballot papers per voter, which means more works for the volunteers. The counting process is slow because it must be witnessed by multiple people.
It will be vastly easier if the ballot can be cast electronically with a machine instead of with a paper. The volunteers need only to worry about preparing the venue then.