I can also imagine a multitude of ways electronic voting can fail or be manipulated without anyone knowing.

Voter turnout was over 84%, and that number has been increasing over the last few elections. We do not have an accessibility problem. For the type of elections we have, the current system is a good fit. One person - one envelope. When the polling stations close the polling clerks take all the envelopes, open them, sort the ballots into valid and invalid piles, and then count the valid votes by hand. It takes a few hours, but we get a pretty accurate preliminary result on election night, and the process is completely open, anyone can watch the counting.

After the preliminary counting all the ballots are sent in to the regional election authority office where they do a second counting where they also add in mail-in votes from Swedes abroad and other people who couldn't be there on the voting day. The second counting is also completely open, anyone can come and watch.

Yes, it takes a few days to get the final result, but the confidence in the result is very high. Yes, there are occasional screwups, but it gets noticed, it gets reported, anyone can notice them, you don't need to a software engineer to have a chance at it.