I think you underestimate the sophistication needed to tamper with paper ballots. There's certainly a "boots on the ground" requirement for tampering, but the knowledge requirements are trivial compared to crypto attacks.
The physical chain of custody can be guaranteed with paper ballots. Yes, you can burn ballots, or stuff the box, but if you're minding the store, someone would notice.
I defer to your expertise but did you ever work in third-world countries? (To use the phrase as a proxy for inadequate political/physical infrastructure)
To use the engineering aphorism, just because it can be done doesn't mean it is done. I'm curious about how physical security/verification works in that environment vs a hypothetical crypto solution.
Observing third world elections is on my bucket list.
Election and voting chicanery happens plenty in the USA. No need to look abroad. Merely lifting the floor here would be transformative.
The silver lining from the oversteer triggered by Gore v Bush 2000 is that HAVA did lead to greater federal involvement in our locally administered elections. eg Election Assistance Commission http://eac.gov is now fairly proactive.
re "vs a hypothetical crypto solution"
Estonia's online voting system hasn't faired well under scrutiny.
If you've worked in third-world countries, you should realize that elections are a human problem determined by societal attitudes. Electoral fraud is not a technical problem.
Knowledge isn't really going to be an issue for the parties most likely to try to swing elections, many of which are state-level actors.
The thing about the crudeness of methods used to tamper with paper ballots is that it's also similarly trivial for a bunch of volunteers including members of all different parties involved in the election to spot, and in many cases trivial to reverse.
Knowledge is not the problem. In fact, knowledge is a trivial problem because with electronic ballots, you only need a single guy with the right knowledge and he can compromise the entire election.
