True, a fully transparent system would require every voter to understand the machine and how the systems prevent tampering.

At the same time, I don't think even a majority of voters know how the voting process works in the U.S. and Canada today, simply trusting that such a process exists. I'd argue that many of the processes aren't even fair, with gerrymandering and spoiler effects being common. Large numbers of people even believe that mail-in votes are simply a tool for fraud.

So yes, ideally everyone would fully understand every step of every system of the voting process, but a working system is possible without that. If a more opaque system could increase verifiability and/or allow faster easier voting, it might be worth it. Of course currently existing voting machines do neither, and massively increase opacity at every level, so they're quite terrible, but I don't think they need to be perfect to be useful.