Let's assume that these people do get the people they want in office by fraud. Do they expect this to continue indefinitely? In a less connected world it may have been possible to win with fraud by small margins and get away with it. Now we have polling with considerable accuracy. People can communicate with an ease and speed that has been unheard of before.
For such fraud to go unnoticed it must be at such a small margin that it can be explained away by a margin of error. If that margin is that small then would not the energy expended on fraud be better spent on making their case to the people? Or, compromising on small matters that people vote on so that larger matters can go their way?
Even though we've made great strides in providing information and means of communication, people themselves haven't changed. They still have their in-groups with similar opinions to their own. They still have their favorite news sources with particular slants that they may never notice. Many still have an inherent trust in the system so they will ignore occasional anomalies of vote fraud as just distractions and not real problems.
And then there's times where the evidence simply gets buried by other news stories or is only covered by fringe, pseudo news organizations that most people will ignore because it's coming from an unfamiliar source.
So yes, theoretically, the increase of information we've during the Information Age should give us perfect elections. The reality is that we'll never have them thanks to human psychology. Let's still try to have legitimate elections though and remain vigilant of fraud wherever it may occur.