You mean election type voting?
Screen scraping is the least of the problems.
Voting machines are simply not trustworthy given these requirements for a free and fair election:
0. Freedom to vote or not
1. Anonymity in that no vote may be associated with the voter who cast it
(These two are most of why e-voting is not trustworthy and are what differentiates banking from voting.)
2. Transparency. The law, means, methods must all be known to the voting public. It is their election. In particular, seeing how a cast vote moves through the entire process and into the final tally is necessary.
3. Oversight. The first two of these foundation requirements necessary for free and fair public elections have an important ratification:
The record of votes cast must be human readable and said record must be used directly to realize the final tally of all votes cast.
There is a chain of trust between voter intent and the vote cast. When one casts a vote on physical media, that is a direct record of voter intent. The voter can be sure their intent adds to the tally because they can directly verify their votes cast.
Electronic votes are a vote by proxy. The direct expression of intent is not kept and exists as a bit of skin residue left on the machine interface. Put simply, we ask people to vote and then we discard their expression!
What gets used instead is whatever the machine thought the voter intent was!
Consider this: You have a machine in front of you with two buttons. One brings the world into harmony, the other casts it into war, grief and darkness.
You can:
A. Submit a paper form you fill out manually indicating your choice
, or
B. Press one of the buttons and get a receipt for your records.
Say this machine has an indicator showing your choice and a third "approval" button you use when you feel good about the machine getting your choice right.
How do you the voter know the receipt and or indicators match what the proxy machine says your choice was.
What happens when we have a dispute? We know the machine can't be trusted to match receipts. With the direct expression of intent lost, what do we bring to court?
We can and have brought paper ballots into court to resolve and election facing genuine ambiguity.
I submit to you we can't really be sure who wins an electronic election, unless we also associate your identity with the vote.
Say a bunch of people get to choose the fate of the world this way. What is your confidence level?
How do we know the machines tallied up the winning choices correctly?
What do the tests for that look like and how do they get around the forced trust problem we have with all electronic inputs today?
There is a lot more trouble to discuss. What I put here is the core trouble and computers have always had this problem too.
It just does not present any real difficulty, until elections are brought into the discussion.
Display trust issues are well above the core tech trust issues we face today.