They could not learn how to read or write it was seen as a privilege only a powerful white man should know.
Oh now i get it.
Well the answer should be in a general election, each state has officials who count and CERTIFY votes.
The officials have to make sure that the people who give their vote have the credibility and rights to voice their vote, to avoid any sort of Election fraud that may negatively effect one candidate.
They were more politically motivated
That is called "Causation" my friend.