Actually, the machines are much easier to manipulate than paper ballots, and easier to use to hide manipulation. They're also extremely unreliable and exhorbitantly costly.
When they fail, nobody gets to vote, or those who thought they voted were thwarted undetectably.
The GAO and NIST have reported on the flaws with these systems, and determined that they're unsuitable for use in elections. They did so for valid reasons.
I write software for scanner systems. Modifying the software to ignore some votes, or to slip them into another column is trivial, and oh by the way, the software for them is on ROM chips in sockets or even better, on removable memory.
Modern voting machines are no less secure than any system that we've had in the past--it's all HYPE to instill doubt in our electoral system.
If I believed in conspiracies, I'd believe that the hype is to make it easier to install a "benevolent" socialist dictator, or to further the idea that only the "ruling class" were qualified and honest enough to vote. But that's not me. I believe that all the hype is because global warming is allowing more x-rays to penetrate the atmosphere and is frying the brains of Princeton Professors.