Canada

Not sure in your riding, but usually, they have different roles and experience level.

One important task is to keep everyone in check. If you reduce that number, the risks of different problems increases. Most recently this

There is a lot of propaganda around the world to discredit elections (usually by authoritarian regimes), so I do not think anyone will take the risk of reducing the number of poll workers.

Elections Canada describes all the roles and processes, from hiring, training, what to do before, during and after the voting day if you are interested in details. https://www.elections.ca/home.aspx

Sadly, we are a bit behind in technology and the costs can persist with electronic voting.

With in-person voting, either we do like Belgium with printing votes (I read people calling it "expensive pen"), or with air-gapped dedicated computers like in South America (the only thing that leaves is one of the storages and a printed sheet with the result of that location). There are the initial investment and we will still need the election workers.

On the other hand, with internet/remote voting, the initial investment in tech, security, and change management will be huge in our current state. You can reduce the numbers of workers with that, but now you will need more expensive people at every step to ensure a fair election.

Countries that uses any kind of electronic voting claim that it improved their elections considerably, including costs, but the upfront cost and the change in culture can scary some people.

(edit: fix typo)