Then the pollster would be confident of matching the election result to within the margin of error 95% of the time.
When the poll and the vote count are outside the margin of error it means there is almost no chance at all that randomness can explain the deviation. There has to be another explanation. One possibility is the vote result is not true. The other possibility is to polling is defective. When you compare 2004 and 2016, you have to ask why would the same polling methods suddenly produce double the error.
Same states with the same Senate races and the same pollster using the same methods, but in 2012 they are off by twice as much plus the greatest error is in Republican-dominated states. In states with Democrats in the Secretary of State position, the election results and polling match much better. In states where the republicans were losing by the widest margins in the polls, the exit polling shows the largest red shift. The red shift even matches how much the election had to swing for Republicans to win.
In the graph above, if the trendlines were flat and matched zero, the exit polls would all be averaging precise and red/blue states would not bias the result. What we have instead is a pronounced red shift in almost every state. The odds of that happening are astronomical.
The battleground states had the most robust polling. This is seen in the match to the pre-election polling. What are the odds all those many polls are also off by the same amount?
A wise gambler would bet the election was rigged if they knew the truth could be shown. A wise politician knows that once an election is successfully stolen, there's about zero chance of proving it, we are just left with these exit polls for solace.