Ranked choice voting is essentially doing multiple elections at a time, having to recount portions of votes every time a candidate drops out. That's a lot easier with computers.
I think the totals from every precinct could be made public in a way that they are verifiable from a central database, where the numbers add up to the total for the state and eventually federal count.
This is probably already happening, but people don't seem to think so.
I agree that for voting systems other than FPTP it is more work and may take longer - but it’s not an intractable problem.
You forgot about 2000. Also, the main reason for the delays are mail-in ballots, which could be delayed for days/weeks, depending on how lenient the deadlines are.
By law the mail-in ballots have to be in by election day.
We need results in as short a time as possible, ws have about 100 crore registered voters, of whom about 70% on average vote, meaning that the ECI must process 70 Crore votes, in under 10 hours.
Making that happen in a free and fair way is a logistical challenge, one that we undertake every 5 years.
One more large advantage of EVMs is making booth capture very expensive (because EVMs have a inbuilt rate limit, but a ballot box does not).
At any rate, with VVPAT being there, it adds another layer of security.
Why do you need the result in under 10 hours?
The US 2000 election was a fiasco of the failures of paper ballots. Officials spent weeks scrutinizing ballots and to this day nobody thinks they got it correct to within the margin of error.
That's when electronic machines came in. They are not necessarily better, but nobody who lived through that nightmare thinks fondly of the clarity of paper ballots.
I lived through that, it wasn't that big a deal, and I still think fondly of the clarity of paper ballots. No system is perfect, but paper ballots work and work well.