Why is so hard to make a working voting machine?

Every once in awhile I read yet another issue with voting machines in the US in different types of elections and regions.

What’s the deal? This latest story isn’t just about vulnerability to hacking but the machines themselves might be switching the votes autonomously. I don’t understand how companies with millions of dollars can’t make a single-purpose machine to securely record the answer to a few multiple choice questions and report the results.

In fact ATMs do that now and are extremely secure, easy to use, and do much more than recording a few simple choices.