Re: your comment on social engineering, etc. There has been a ton of effort in arenas in the US electoral system(s), but the goals have not been security or access - sometimes quite the opposite.
The problem is that an individual ballot in RCV if counted manually, needs to be counted several times if the vote ends up switching to the 2nd, 3rd, or fourth choice etc. As the number of total votes increases from the thousands to hundreds of thousands (or even millions), this can cause a pseudo-exponential growth in the amount of counting labor performed. Large municipalities that have trialed RCV have forged ahead with manual counts and succeeded despite the increased effort, but it has sometimes taken days to report results. That's only after massive amounts of labor from volunteers.
Going statewide with manual-only counts of paper ballots (no optical scanning or other machine-assisted counting) makes RCV or other methods of determining winner much more difficult because of the labor or cost involved.
It should be clear that I quite like RCV, but this is a factor to consider.
Personally I'm a fan of just committing to doing it by hand and accepting the cost in exchange for robustness against many types of manipulation. The problem is your argument works the other way also, the easier/cheaper it is to tally the votes due to reduced labor and # of people involved, the higher the risk of significant interference, imo.