I don't think number of fraudulent votes is important as much as percentage of the pool those votes in terms of detection. Yes a state election can be flipped with a much smaller amount of votes, but that smaller amount will be more glaring.
Also here is the red sox post since you have him blocked.
That scenario isn't because of the Electoral College, it's because of the method for aggregating votes from different states. If you had the election decided by a national popular vote, Pence would still have been opening envelopes containing the vote tallies from the different states. Only it would be even more prone to abuse at this stage of the counting because any red state could have submitted a fraudulent vote tally asserting, let's say, that the entire state population had voted for Trump when it was really a 55/45 thing with 70% turnout.
What would Pence be supposed to do when presented with such a hypothetical vote tally? Count it anyway because his job is only ministerial? Refuse to count it because of obvious fraud, opening the door to other VPs rejecting legitimate vote tallies they don't like? With the EC, the margin within a state doesn't matter so this kind of scheme wouldn't achieve anything.
To me this feels like you're attaching baggage to the EC when a lot of these procedures exist relatively independent of the EC and would carry over to popular vote as well because why wouldn't they.