It is far easier to stuff the ballot box with fraudulent paper ballots than it is to hack into a computer. It is very easy to simply throw away paper votes for your opponent and replace them with votes for your party.
Any type of voting system is capable of being used for voter fraud. Honest elections depend on the workers at the polling places. Most of them are volunteers or are paid a nominal amount but they are what keeps American elections honest. If they are dishonest, it doesn't matter what kind of voting system you have.
You make a great point. It doesn't matter if we have electronic, paper, or both without an accountability system.
Votes show up from no where without any chain of custody and are accepted by judges as actual votes. These same judges would then never allow evidence into a trial without the chain of custody. I don't think any vote should count without a verifiable chain of custody. Also, I don't think anyone should cast a vote without proper ID.
Finally, absentee balloting should be outlawed. I'm sorry if you can't make it, but I would rather disallow legal voters than allow one illegal voter.