As a person who's from a country with, let's say, VERY VERY contested, controversial and eventful elections, the fact that independent poll watchers from different parties and NGOs can independently observe ballot boxes, take photo evidence of countersigned and publicly posted box tallies to send them to their HQs, and then compare and contrast results amongst each other as well as with the official results is a huge boon for transparency and trust in the electoral system.

It's not perfect: more remote and less popular areas go unobserved, and what happens after an official complaint is made is anyone's guess.

But at least almost anyone can add up numbers for themselves and come to a conclusion about what to trust and not trust. And you might think no one would bother, but in my brief experience as a volunteer poll worker they surely do, and zealously so. I can't even begin to imagine what'd happen if the paper ballot was replaced with "trust us, the machine says 37 for party A" or "the magical fingerprint number you don't understand says this ballot was cast for someone else".