I live in California, where the voting method is vote-by-mail and you sign your ballot. That breaks anonymity right there, plus there's a barcode that matches address and ballot for traceability, so in theory anyone involved in the election process could look at my ballot, cross-reference against address, and figure out how I voted. In practice I've never heard of anyone being pressured or confronted based on how they voted, so my default assumption is this doesn't happen much or at all.
But even broader, in the U.S. your party registration is public information. That's why whenever there's a political shooting, the media always says "He was a registered Republican" or "registered Democrat" or "was not registered to vote". And this mechanism is actively and publicly being exploited to alter elections. Since the U.S. is a two-party system and party membership is public, you have a fairly good idea how each precinct is going to vote before they vote, and can gerrymander maps to get the outcomes you want.
Plenty of trust issues in physical ballot transfer as well. California is vote-by-mail, but that assumes the postal service is a reliable carrier, while there was just a recent news story [1] about ballots being stolen. Before I lived in California, I was in Massachusetts, where we voted on 1930s-era lever voting machines where you hit a lever down and it marks a paper ballot without you ever seeing the real ballot. Between elections, these were stored backstage at the local middle school, so a mechanically-inclined middle schooler with knowledge of how an upcoming election's ballots would be formatted (and we did mock elections in middle school) could have rigged the machines to deliver the local precinct to their preferred candidate.
The useful points in the video were basically that decentralization and redundancy are what make physical elections hard to rig: you have to hack multiple locations to influence the overall election, and at each point you have multiple eyes watching you. He sets up the contrast with software voting, where you have the same software running on each machine, and even if the software is open-source, you can't be sure that the rest of the stack it's running on is secure (an oblique reference to the Ken Thompson Hack [2]).
But decentralization and redundancy are properties that you can introduce into software systems just as easily as real-wold systems. The KTH can be countered through Diverse Double-Compiling, for example [3]. zkStarks and digital signatures give you ability to prove that you authored something without revealing what that something is or who you are. The importance of client diversity for the security of the network as a whole has been well-known in the filesharing and crypto worlds. And anyone who has worked in Big Tech, aviation, or telecom could tell you that having multiple paths to success that are developed by independent teams is important for any computer system that is in a safety- or reliability-critical area.
[1] https://www.almanacnews.com/election/2025/10/14/ballots-stol...