It is possible to do small-scale fraud with paper ballots, you can never fully eliminate that option. But it is exceedingly hard to do larger scale fraud without it being extremely obvious to any observer.
Yes, I know: before computers and other mechanical systems, people had to count ballots by hand. There were many fewer people voting then, and regardless, that's not really the point: they counted by hand because they had no alternative.
Electronic voting certainly brings new problems into the mix. I don't think those problems are insurmountable. The problem isn't the technology itself. It's the legal and social landscape around voting technology. Open source, with reproducible builds and a method to verify that the code running on a machine was built from a particular version of source, is a start. Verification of that software's functionality, on par with the verification done of critical software (medical devices, things that go into space, slot machines, etc.) would be another good move.
Voters can also receive paper receipts, and I'm sure we can come up with some sort of scheme to take a representative sample of the electronically-recorded votes and validate them against the paper receipts, while maintaining voter privacy.
Other countries do paper ballots and manual counting without issues. The US isn't that special or unusual.
As soon as you try to be more clever than electronic counting of paper ballots, yes they are.
You can either audit the count by replaying the input event stream, or you can't.