You speak as if I'm advocating for e-voting systems over paper voting systems. I'm not. In general, most paper voting systems that are used in practice are more secure than most e-voting systems that are used in practice.
> 1. Paper ballots are in some ways more ambigous, because there are many ways to scribble a sign into a circle, a fraction of which will not result in the intended outcome
Look, I tried to cover all aspects of how the integrity of the voting results can be compromised. There are big issues, like a foreign superpower attempting to hack the results, and then there are small issues, like this one: people accidentally spoiling ballots.
I'm struggling to understand why you feel the need to attack this minor point in my thesis with words like "ridiculous", "disingenuous" and "unscientific". Accidental spoiling is a real issue that happens and I even have a photograph of an ambiguously marked ballot in my thesis.
> 2. Understanding these handwritten symbols is harder than understanding the electronic system, because of that ambiguity
I wrote in Appendix B about how accidental spoiling could be resolved by adding electronics, but _only_ adding them to fix this specific issue (_not_ replacing the whole voting scheme with black box computers that can be hacked). When you say "the electronic system", it sounds to me like you are imagining something more.
Let me try to illustrate this specific point from Appendix B.
A) Fully paper system. You walk into a voting booth. You scribble down the number "7" on paper. You walk out of the booth and put the paper in the ballot box. Later some election official is counting the votes and they look at your scribble and they wonder, hmm, is this a "7" or is this a "1". Your vote is disqualified.
B) Same system but augmented with simple electronics to prevent accidental spoiling. You walk into a voting booth. You scribble down the number "7" on paper. Inside the booth you insert your paper into a scanner which interprets your scribble and prints out a new paper that is supposed to contain your vote. You look at the new paper to verify how your vote is going to be interpreted and you see... what the heck, it's a "1"? Why is it a "1"? I wrote down "7"! So you take a new paper, and now you very clearly write down "7" on the new paper and scan it again. The computer now prints out a paper that has a "7" on it. Good. So now you walk out of the voting booth and then drop the paper with the computer-written "7" on it into the ballot box.
See how B) is exactly the same system as A) except it offers voters the ability to see how their vote is going to be interpreted, before they cast the vote into the ballot box? The machine inside the booth doesn't have to be connected to the internet and it doesn't have to do anything more complex than read a number on a paper and then print the same number. If somebody hacks the machine to "misinterpret" votes, it will be caught very fast.
> 4. Trust in voting systems does not primarily arise from understandability but from trust in other people.
> And as computers can be reprogrammed, potentially remotely, even your experts can't be sure – especially in elections where powerful nation state actors seek to destroy the public trust in your election. This is a problem – just claiming that it isn't doesn't cut it. And people who claim that it isn't should not be the ones designing such systems.
The whole point of a verifiable voting system is that you don't have to trust the election computers. Even if all the official computers are hacked by Russia, I can still run the data on my own machine to verify the results of the election. As long as there is one clean computer in the world and one nerd who cares, the truth will come out.
And I'm not "just claiming that it is [verifiable]" - I wrote a whole thesis on these voting schemes. I did my best to identify the strengths and weaknesses of each scheme and as you can see in the comparison table, each scheme does have their weaknesses. A "perfect" verifiable voting scheme does not exist. That said, it sounds to me like you are imagining all electronic voting schemes to be "black box" schemes relying on blindly trusting both authorities and computers, and that is not the case at all. I would suggest that you familiarize yourself with at least one of these "verifiable" voting schemes before criticizing them. If you are interested in further discussing the specific weaknesses of a specific scheme which incorporates some electronic aspects, I would suggest that you read the description of "Floating Receipts" scheme from my thesis and then we can discuss specifics of that if you like.