Prior to widespread use of electronic voting machines in the last decade, exit polls were a reliable prediction of election results. Since widespread use of electronic voting machines, election results have not agreed with exit polls.
The only two possible explanations have been that either voters have not been honest about who they've voted for since they started using electronic voting machines or election results have been manipulated by electronic voting machine companies.
Electronic election ballots are counted in secret by voting machine companies, and not shared publicly. Electronic election results have consistently favored more conservative candidates when compared to exit polls. The owners of electronic voting machine companies primarily support more conservative candidates.