I thought about some advantages of paper voting compared to electronic: you can spoil the ballot, for example, if you don't like any of candidates and there is no option titled "Against all". In electronic elections, you cannot do that.
Here's a case from last week of a spoiled ballot giving someone a majority of one: https://www.theguardian.com/politics/2019/may/03/ballot-pape...
Was that the result the voter intended? Probably not, but who knows? :)
This was a constituency where the previous incumbent had had some problems with his younger GF
Not bothering to show up at all doesn't give any clear message.