You can say this with 100% certainty? Bold statement.

It comes from the system that we have in place. Every part of the ballot counting process is observed by the GOP and the campaigns. Same for the Democrats. This part of the elections process is transparent and subject to real-time review at every location. It's implausible to the extreme that one could engage in enough "sketchy" behavior to actually change the outcome of a Presidential election, which even in the tightest races is almost always decided by tens or hundreds of thousands of votes. There's no actual opportunity to gain anything by engaging in sketchy dealings - anything big enough to matter would certainly get caught, and anything small enough to get caught isn't going to matter.

So yeah - pretty confident that regardless of whether you think the poll workers and canvassers are good people or evil black-hearted scoundrels that hate America, the measures we have in place make it implausible that they're engaging in sketchy behavior.

Uh, huh.
So it's all a matter of perception, and Republicans are just lied to all the time?

You don't understand how unique the attacks on the ballot counting process were? Republicans aren't lied to all the time - they were lied to in connection with the 2020 election. In almost every other election - and certainly every other Presidential election - the votes are cast and counted, and the losing candidate concedes without accusing the other side of rigging the ballot counting. Because the losing candidate knows that his campaign staff - all the poll watchers and canvass monitors and lawyers and what not - were watching every step of the counting process, and if anything actually untoward had happened in the counting process they would have duly run off to court and said so to a judge. So that even if random third party folks were out there complaining about crazy stuff, the person in charge of all of the monitoring of the counting - ie. the candidate - would have given the word that the counting was legit.

Trump was different. Uniquely different. He insisted that the Democrats cheated in the counting process. He didn't acknowledge that if the Democrats had cheated in counting the ballots, his team would have seen it happen. No, he just went out and told everyone the election was being stolen from him.

I'm sorry to have to say this, but I see zero reason to assume any democrat politician -or- left-leaning media outfit operates with a shred of integrity. That's done with; when it comes to truth-telling I automatically assume every democrat I'm listening to is either wrong, lying, obfuscating, taking things out of context or leading with a dishonest premise.

So again, we're back to the point you were trying to deny. The right wing is going to assume that the election wasn't fair, that the count wasn't fair. It doesn't matter whether there's any evidence that it happens, or the irrationality of thinking that someone could rig the count given the level of opposing-party monitoring. So any election where Trump loses was unfair and rigged, and only an election that he wins can be fair. Which - I'm not going to be able to disabuse you of that, but you do see where that shows that it doesn't really matter whether any sketchy things actually happen, but flows inexorably from the starting position of the right wing that the Democrats are ever and always cheaters?