To thin the herd on the Senate ballots they could just up the number of people required to register. They could also up the deposit a bit, although doing that by too much would be undemocratic. I personally don't have a problem with a large ballot, and nobody I've spoken to has one either. I understand Antony Green has a bee in his bonnet about it, but is there actual evidence that the large ballots are a problem? I haven't seen any.

A machine approach to the Senate ballot would also be problematic as you'd also have to display the candidates across multiple views on an app. Should said app have a "next" button or should we swipe to the next "card"? Should it scroll? Will older people know how to scroll it? Is some "GUI rockstar" going to inflict a drag-and-drop candidate ordering on us? Which OS are we going to use? Is the nation where the hardware is made democratic or does it have to be made here? I can see it ballooning in complexity as many government run IT projects do. The paper ballot, perhaps with fewer parties via the mechanisms I highlight above, is solid and proven.

Existing electronic voting systems provide a guide for what to expect. There have been US cases where the touch screen was so poorly calibrated it was selecting the wrong candidate, cases of election officials taking machines home (machines later proven to be hackable with that kind of access), in some places there weren't enough machines provisioned. The security question extends to the machines for weeks before the election, they have to be protected for all that time. And now you need the equivalent of IT support services at every polling booth, or a significant increase in the costs of training the volunteers. I can't see how all of that, on top of R&D and the cost of the machines, is going to cost less. Also how do you handle a power outage on polling day? Or do we need to add more complexity, and fork out even more money, to have batteries sufficient to handle a whole day power outage? What happens when someone pours some water into a machine with 10,000 votes in it near the end of the day?

You can't say, as you did in your reply to someone else, voting machines have “different security problems rather than more”. They are more complex, more complex things can indeed have more security problems. A computer has more potential security problems than a piece of paper. That's why the Russian FSO, who know a thing or two about security, are buying typewriters.[1]

Most times these arguments boil down to the machines having to print out a paper ballot or receipt to be credible, anyone who has dealt with computers and printing knows what a barrel of laughs it's going to be to have people dealing with jammed machines or machines that are out of paper. I can picture an irate voter having their ballot secrecy violated as their crumpled ballot is pulled out of the slot by some highly paid technician. And given the spacing of elections, the machines would become outdated quickly so we'd have to go through the whole rigmarole of designing or commissioning new ones every three or four electoral cycles.

Finally, I don't think we should underestimate the benefits of getting large numbers of people involved in the counting. There is a social good in getting those volunteers to become knowledgeable about the process. They carry that civic knowledge around with them so it's available when someone needs the Senate voting explained to them at a weekend BBQ or someone wants to run an election for a role in a non-profit or a club.

[1] http://www.bbc.com/news/world-europe-23282308