The use of voting machines has been ruled unconstitutional in Germany: http://www.bverfg.de/e/cs20090303_2bvc000307en.html (English version of the ruling!). Only paper ballots are used in Germany, and they are counted by hand. This article is about the software used to tabulate and transmit the hand-counted vote counts.

On the supreme court decision: the key section is "When electronic voting machines are deployed, it must be possible for the citizen to check the essential steps in the election act and in the ascertainment of the results reliably and without special expert knowledge." - since it's just about impossible to build a voting machine in a way that anyone can convince themselves of its proper operation without special expert knowledge, voting machines are effectively unconstitutional. Everyone can follow the process of counting votes on a paper ballot.

I'm old enough to remember "hanging chads" and "pregnant chads"... Paper isn't perfect but I tend to agree.

Why? Can you provide more detail?

I really like Tom Scott's explenation: https://www.youtube.com/watch?v=w3_0x6oaDmI

It can be inspected and visible. You cannot verify a computer is running the exact same code you want it to be.

In a properly designed end-to-end verifiable voting system, you don't need to verify the code. Black boxes work just fine, you need to be able to verify that the output had indeed matched your input.

I'm not advocating use of computers, though. Believe paper ballots with some math attached are the way to go. That way there are both anti-fraud properties baked in the system (one can verify that their vote wasn't messed with), and the classic hard copies so any person who can do some basic arithmetic can count and re-count votes just fine.

Unfortunately, I think all the systems I've read about either were found to have some issues (usually, it's about vote secrecy) or just too new (essentially, not so well reviewed).

In order to verify the output matched the input, you will need paper and to verify it by hand. Which, is just a waste of time adding computers...

Not really. To verify, you need to perform the computations using the tools you can trust. It can be pen-and-paper-and-brain, or it can be a personal computer.

It's also totally unnecessary to use computers. Paper ballots work just fine.

even then those counting the paper ballots can be biased.

That's why literally anybody can volunteer and there're lots of people from different backgrounds counting the ballots and checking each other.