> your scenario is not observed in the wild, since it is illegal.
I don't mean to be snide, but I've witnessed a great deal of illegal things, so "since it is illegal" is not that convincing.
Even if you discount the threat of violence because of the possibility of police intervention (e.g. you report being threatened), consider the notion of vote buying: a rich person just says they'll pay you lots of money to vote for them. This isn't necessarily something people would want to report, given the possibility of financial benefit, especially if the person is down on their luck.
At any rate, if electoral fraud is something that is "not observed in the wild", people sure do make a big fuss over it (see http://en.wikipedia.org/wiki/Electoral_fraud for some references).