Apologize for not referencing more evidence for the counterview.
So let me bring up some exhaustively prepared articles from the past. A lot of these are from the late 2000s when the "voter ID" issue was in play, but I do not think the electoral landscape has changed that much since then.
A report on voter fraud in 2007 from the Brennan Center concluded a very low rate of voter fraud in 2004.
http://www.brennancenter.org/sites/default/files/legacy/The%...
News21 (part of the Carnegie Knight media initiative) created a database of voter fraud. They found little.
http://votingrights.news21.com/article/election-fraud/
We have this Washington Post reporter who tracked voter fraud, and found little.
https://www.washingtonpost.com/news/wonk/wp/2014/08/06/a-com...
And... another paper on how "voter fraud is in the eye of the beholder." (Harvard Law Review)
http://www.harvardlawreview.org/wp-content/uploads/pdfs/anso...
So... that's a lot of data (I could link many more reports from this era) that indicates that, frankly, voter fraud from any angle really hasn't been a big issue before (and that any perception may be due to political bias, perhaps). I do believe there's plenty of inefficiencies regarding the American electoral process, and that might be right ("inaccurate, costly, and inefficient" as the Pew Center on the States alleged in 2012, that I buy -- http://www.pewtrusts.org/~/media/legacy/uploadedfiles/pcs_as...). But there's a difference between incompetence and awful systems, and outright fraud.
I must acknowledge that this isn't the only paper alleging fraud in the 2016 primaries (https://drive.google.com/file/d/0B6mLpCEIGEYGYl9RZWFRcmpsZk0...). I will note however that, for this one, Snopes was skeptical in that the numbers had not been peer reviewed by independent parties (http://www.snopes.com/stanford-study-proves-election-fraud-t...) and note counter-viewpoints ala Joshua Holland of The Nation (who does not think much of "exit poll conspiracies": https://www.thenation.com/article/reminder-exit-poll-conspir...)
This is why I'm very cautious. Bias is huge in politics; it may be exhaustively prepared, but if they are using bunk statistics, it's not worth much.