This is a tautology. You're saying that in every election where fraud was obvious ("democracy actually left"), fraud was obvious.

There is probably a lot more subtle election fraud that is never detected.

Hmm... I'm trying to say in every election that was manipulated, it was not subtle fraud that was the problem. I have little doubt that some fraud happens. I just don't think it typically matters. In most cases where it was not detected, it had no bearing on the outcome.

Now, overt manipulation of the voting populace through propaganda or other means is very common and has definitely happened. Ballet fraud, though? Are there any documented cases of that being a thing that mattered?

See e.g. https://en.wikipedia.org/wiki/Yugoslavian_general_election,_...