In the US right now, our problems are well understood and primarily relate to ensuring that only legally eligible people vote, and that the vote was cast by that actual person.
These are fundamentally not technical problems. We have known about them for decades if not centuries and as recently as the early 2000s the Carter-Baker commission laid out the problems and the relatively straightforward solutions.
There have always been political “machines” in big cities, and if given the opportunity, they will try to stuff ballot boxes, intimidate voters, harvest ballots, exclude observers, apply voting laws unequally, and do any number of other shenanigans to give their party an advantage.
This has reached epic proportions since mail-in ballots for able bodied voters was normalized during COVID.
And the problems have all been exacerbated by the unwillingness of the courts to force states to abide by their own voting laws.
Election administration is not difficult, it is a straightforward set of tasks that require diligence and integrity, and that benefits greatly from having highly motivated partisan observers at every stage of the process.
Technology currently used in voting mostly just introduces more ways to mess up elections either intentionally (via manipulation, by administrators or hackers) or accidentally (as via bugs).
The fixes as I said, are simple but inconvenient:
1. Diligently clean voter rolls every year, or even throw them out and restart every year
2. Strongly authenticate voters via in-person registration with trusted nonpartisan agents (government officials) and verify eligibility to vote (citizenship, residency, age, selective service)
3. Vote in person. If intimidation is known to be a problem in a precinct, bring in state police (not local). Note that machine precincts are likely determinable via statistical and electoral analysis, eg where can small swings have big electoral impact). You don’t have to fortify everywhere.
4. Check voter id at the polls.
5. Paper ballots, hand counted on the day of election.
6. Invalidate the count and require revote from any precinct that counts any vote not in the presence of partisan observers from any party on the ballot that asks. Do not allow any vote to be counted after results are reported; the remedy for custody mistakes and “finding uncounted votes” is re-vote.
7. Publicly post precinct level results BEFORE reporting to the county or state. Publicly post county results before reporting to the state. This allows independent channels to confirm that tallies at the county or state level are not tampered with or inadvertently miscomputed.
8. Fast track any election challenge hearings from any eligible voter in an election and do not allow judges to reject cases due to standing, mootness or laches.
9. Absentee ballots should be rare and require proof of need and extraordinary verification with partisan monitoring.