Well, they're getting sued by the voting machine manufacturers for billions of dollars. It was all fun and games until financial liability was on the table.
Bush's election definitely hurt trust in elections. And the Democrats didn't do themselves any favors by continuing to peddle misinformation about Russia. Neera Tanden was continuing to say Russia stole the election years after Trump's election (complete with the implication that they actually changed votes, if I'm remembering correctly). Clinton, too, would peddle that bullshit when she wasn't too busy blaming Bernie or misogyny for her loss. If you spend 4 years peddling the line that Trump stole the election, you can't be surprised that people trust in elections declined.
Plus, there's the simple fact that the US electoral system is fucked. If someone presented you with the system of the electoral college, winner take-all systems of electors, elections where the majority vote may not win because of how electors have been weighted, election results that sometimes take states weeks to actually finalize, news networks declaring the election results on election night in spite of that, and on & on... would you trust it? On the face of it, it's completely insane. Every single peer nation of the US conducts elections better than we do.