Ah yeah I forgot. The (monetary, personal, logistical, time) cost of doing fraud has to be as high as possible.

This would be another point where digital solutions usually turn out far worse than traditional paper ballots. If you can hack one machine you potentially could manipulate many ballots. If you hack the manufacturer of the machine you potentially get many machines – and this could be done by a single person with the right information and skillset.

That makes a digital attack feasible for a nation-state-attacker, of which there are certainly some (and maybe more in the future).

Paper being slow, cumbersome, material-intesive is not a bug, it is a feature.