Voting machines do cause problems, see 2000 presidential election. Best practice appears to be along the lines that CO, OR and WA do, mail human marked paper ballots to every voter, allow in person voting. The paper ballots are both human and machine readable. After a count, human or machine, perform a risk limiting audit.

There's a good paper, "A gentle introduction to risk limiting audits", Mark Lindemann and Philip B. Stark, on the topic.

This kind of voting increases participation, decreases costs, a win-win. Anybody advocating for in person, same day voting, or using voting machines has not worked through the issues, or wants to suppress voting.

Yes. It goes into the history and also how paper ballots were sabotaged.

I’m surprised any code can be changed without an audit.

In Germany there was basically 20 years of "digital is the future, so voting has also to be digital" in media, politics etc. However, because Germany is a digital laggard, it just never happened, which is why the waiting time was long enough for the opinion to change enough that nowadays digital voting is not even in discussion.

See, sometimes waiting solves problems. So, TL;DR America was too quick with digital voting, which is why it became entrenched. Should've been laggards like Germany.