In addition, most states have a mechanism by which a candidate can formally challenge the results in a precinct, forcing a hand-recount. This usually has some kind of onus on the requester (I believe in PA for example you have to put up a bounty and if the hand recount results come out to the same result as the previous tabulation the state keeps the bounty as payment for the added cost of the forced audit). However, it is an option (and, most notably, not an option that anyone who claimed shenanigans in 2016 or 2024 exercised).
The problem of election integrity doesn't exist in a vacuum and didn't pop up overnight in 2016; states have been working the issue for a couple centuries and have a pretty good system. But it's a system that requires some detailed statistics and process control theory to understand, so I'm not surprised the median voter doesn't get it. There is, perhaps, a case to be made that for that reason alone we should go to manual, but someone's gonna have to spend the money on that if we're going to do it; it's going to be drastically more expensive than electronically-facilitated counting. And, indeed, people will have to accept that human counters will be less accurate than machine counters (because they're human; we don't train "computers" anymore as a discipline).