Same in Italy, each party can have one person observing proceedings. There used to be tons of parties, hence there were lots of eyes around. The better-organised parties also tracked in realtime whether their sympathizers had actually voted, seat by seat, and could send messages through relays to hurry them to the booth. Before computers, journalists typically relied on the major parties to have the first results, well before they were officially declared.

This has changed in modern times, as a number of parties disappeared after electoral reforms; and the risk of tampering and shenanigans has increased substantially.