There’s so many things wrong with digital voting. The biggest being that it’s so easy to hack compared to analog (paper) voting. You want to change an election, just hack the machine. With paper, you need a grand conspiracy.
(Or you need a country where those third party observers are already powerless, but that's beside the point).
If you're the secretary of state for a given state of the union, and you're in charge of the voter rolls, and you're running for office, then you are fully empowered to just remove anyone from the voter rolls who has a name you don't like, or who has a race you don't like, or who has a political affiliation you don't like.
And you can stymie all attempts to uncover your malfeasance by just shoving all those requests in the drawer, where they get mysteriously lost.